C10 to K20 Project: The Green Truck

vgreen

Putting the G in RGB
Howdy everyone! I have been away for a few years. Last time I was active on here, I had a 95 Montero SR. I sold it to my brother a few years ago and have been without a 4wd vehicle since. I have now started a project to rectify that problem. If I am honest, it will never be the kind of vehicle you would want to travel the world in, but I am going to post here anyway because it will see plenty of exploring and offroading in the spirit overlanding. These first few posts will be bit wordy, so I apologize in advance.

About 5 years ago, my father-in-law gave my wife and I a really nice 1978 C10. He didn't want to sell it, but had little use for it anymore. I was more than happy to take over stewardship over what I saw as a family heirloom. The truck has been in my wife's family almost since new. My father-in-law bought it in 1982 from the original owner's widow I believe. My wife actually came home from the hospital in it. It was the family vehicle for a few years, until more children came into the picture and necessitated the moved to a Suburban.


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The truck has been through many iterations under my father-in-law's ownership. It was originally a heavy half with a 350 and a th350. At some point my father-in-law swapped a 454 into it, before putting a worked over 350 back in. He put the 15x10 turbine wheels on and had the bench reupholstered and swapped in a 3.73 rear end. It was originally a two tone green, but sometime in the mid 90s he had it painted a metallic green and all the trim running down the side of the truck removed. He also had the body guy put standard mirrors on it in place of the larger towing mirrors. Mechanically, it has a rebuilt trans and the front end was all replaced in the 90s as well. It has a great 350 in it. It's got an estimated 10:1 compression, later vortec heads, an Edlebrock intake and carb, and a mild cam. I believe it has flat top pistons. I don't know the specific cam, intake, or carb, and my father-in-law doesn't remember. From my limited research, it seems like that recipe could be good for 350hp. It can get out of its own way for sure, but needs some tuning. I will need to learn to tune a carb and distributor!


Currently, it looks great from 10 feet, but has a few bruises when you get close. The bench needs reupholstered again. It's not a show truck, but drives great, gets lots of compliments, and has proven very reliable. It has only needed a battery, wheel bearing, and oil changes since I have had it. It now needs new tires and some other odds and ends.


My father-in-law had a bit of a sport truck vibe going with the turbine wheels and 275/60 tires. Now that I have taken over stewardship of the truck, with my FIL's blessing (and help), I'm transforming it into more of a classic work truck and converting it to 4WD. I have lots of reasons (*cough* excuses *cough*) for doing this, but it all started because I just missed having 4WD around, but I consider the truck a family heirloom and I don't want to part with it! My wife is very accommodating, but I would have trouble justifying a 4WD SUV or pickup AND the C10.


So, in order to have my cake and eat it too, the Green Truck (as it is known by everyone) will become a multipurpose vehicle. It will be a 4WD camping/exploring rig, a classic project vehicle, and truck for towing/hauling things when needed. I have a 2.5 year old daughter, and I have visions camping and fishing with her in the next year. Maybe if I find a camper for it, my wife will join too. Another bonus of this plan, I also don't have to give up my sporty daily driver.


So with all that background, on to the project part: A few months ago I purchased a 1980 k20 with an sm465/np205 and a 350. Let me start off by saying it was super cheap, and I feel that is important to remember before I start describing it. I picked it up for $500. These trucks are getting harder to find and more expensive. This was by far the cheapest thing I found that met all my criteria. I toyed with the idea of paying more for something in better condition, but in the end I figured I would be going through all the systems anyway, I might as well start with the cheapest thing I could find. I wanted a 3/4 ton, manual trans, and a fairly stock suspension as a starting point. This truck fit the bill.

So on the to the description. The body was rusty and full of holes, the floors were being held together by three layers of floor mats screwed into areas of solid metal, the carb (at least, if not the heads as well) was full of water, and it had a 2" or so lift cobbled together with square tubing "blocks" in the front and "ambulance" springs in the rear. The previous owner couldn't find the keys or the title. I'm pretty sure the truck had sat for close to a decade, judging by the sticker on the license plate.


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On the plus side, it had 4 straight factory 16" steel wheels with hubcaps that are mostly free of dents. Which is good, because the end goal is a mostly factory looking truck. It also had the 10.25in FF 14 bolt and the big drum brakes. The trans shifted well and the axles didn't have any obvious leaks or issues. In the end, it was cheap and seemed perfect for my plans, so it went home with me despite its numerous issues.


Actually, it sat at my brother-in-law's house for a month or so first! His wife was thrilled.


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Because my father-in-law has a huge shop and I only have a small spot next to my garage, much of the work will take place there. My wife's family all live a few hours away, which complicates things a bit. So the was to first remove the body, engine, trans, and transfer case of the K20. My father-in-law, who has a truck and trailer and is retired, will then deliver the rolling chassis to my house, where I will clean it, paint it, and do anything else I can to prep it for the next stage. At that point, it will travel back to his house where we will merge it with the body and engine out from the Green Truck.
 
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vgreen

Putting the G in RGB
Continuing with my saga, back in January my FIL (I'm going to use that from now on because I am sick of typing father-in-law) and I tore into the K20 over a weekend. Out of the entire body and interior, the only parts I pulled off that weren't rusted, tweaked, bent, cracked or otherwise rendered useless were the headlight surrounds. Literally everything else was garbage. Actually the rear bumper will be reused, after getting cleaned up and a coat of paint. There was some salvageable parts off the engine, but it was completely locked up. We didn't spend too much time messing with it.

The mostly bad things I discovered:
Unsurprisingly, the front end needs rebuilt. The lines to the steering box were disconnected and the it was full of water. All the balljoints long ago seeped out all of their grease. The draglink is bent. Moving rearward, the front driveshaft u-joints had no needle bearings left. There is enough mud caked to axle housing, transmission and transfer case that I can't make out their true shape.


The bed used to be painted red. Another interesting thing I discovered was that while right tank appears to be the original 20 gal tank with a steel skidplate, there is fuel filler on that side of the bed. The left tank is a 16 gal tank which I didn't think was ever offered on a K20. I am guessing the left side got hit at one point and the bed and left tank were replaced in the cheapest possible manner.

The rear "ambulance" springs were just set on the axle, the stock springs set on top of those, and it was all bolted together with homemade plates and u-bolts. I bet this thing rode like a dump truck.


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The obviously professionally installed rear springs


The worst discovery of the day was mud-filled front spring hanger on the right rear. While digging the mud out of it with a screw driver, I was able to poke a hole in it. Mud sitting in it for year apparently rotted through. So that will need replaced. Luckily, the rest of the frame is very solid. Overall, the spring hanger was the only thing that was unexpected. Everything else is either coming from the Green Truck or I was planning on replacing anyway.


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And now last week, the chassis was delivered to my house. You guys are now all caught up with my project/life story. At this point, I'd also like to point out that I have the best father-in-law in the world. My wife jokes that he is the real reason I married her.


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I still need to figure out what gears are in it and if there is a traction-aid of some sort in the rear axle. Future plans include a 2-3" lift and 255/85s on the stock 6in wheels. I'm still researching how I want to achieve that lift, but I am leaning towards ORD shackle flip in the rear and the EZ-ride springs they offer for the front.

In the distant future, I'd like to repower it and add a trans with an overdrive. Larry and amazing K10 and K20 suburban have me pretty convinced it should be a 8.1L, and have provided LOTS of inspiration!
 

rayra

Expedition Leader
Some bold alchemy. Sounds like a fun project. I've had my '85 since '86, 350k+ mi on it and I could never even muster the drive to put an overdrive in it, much less convert it to 4wd.

if you aren't already aware of them, LMC Truck may be of great use to you.

If you still have the original carter / rochester / QuedraJet in it, I encourage you to look at the Edelbrock replacement carb, no penetrations in its body, can't leak like a Q-Jet always does.
 

vgreen

Putting the G in RGB
Thanks rayra. Bold is a nice way to put it. Another title for this could be "deranged man ruins perfectly good truck."

My knowledgeable FIL actually replaced the quadrajet with an Edelbrock for that very reason, he could never get it tuned well and it leaked on him. He worked out lots of bugs before handing it to us.

How is the quality on LMC parts? I've got a catalog sitting here, but I've never ordered from them. Also, I was bummed when I realized they don't offer green interior parts. Seems it's red, blue, or black.
 

chilliwak

Expedition Leader
Welcome as an active member of the site Vgreen now that you have 2 great square body trucks. Looks like a good project you have going there. I drive a 79 and have done lots of upgrades over the years. Look into BDS suspension for new leafs. Good prices and an even better garantee. My truck has a do it your self dual front shock set-up that is easy to do on these old pick ups. Check out my build thread for details and pics. I am looking forward to seeing all your progress on that fine old Chevy of yours. Keeps us updated with lots of pics. Cheers, Chilli..:)
 

vgreen

Putting the G in RGB
Thanks Chilliwak, I just checked out BDS springs on your recommendation. They seem like a great option. I will definitely check out your build thread!
 

mccustomize

Explorer
Check out Brother's truck parts, they seem to have some of the stuff LMC cannot get and the parts seem to be a little better quality as well. I envy your project, I'm in the process of a frame off build on my 2003 Silverado and it's quite an undertaking!
 

vgreen

Putting the G in RGB
Wow, mccustomize, I am envious of your fabrication skills! I just read your whole build thread, very impressive. I read your trip report for the Ozarks Challenge, as well. I live in Fayetteville and I was supposed to be the navigator for a team in 2015 (I think?) but a newborn and grad school prevented it. I know how tight those trails are, though, impressive work.
 

rayra

Expedition Leader
There's a range of quality with LMC, but more often it's a choice of their stuff or nothing. GM dealers don't even stock the unique items for these trucks anymore. Just try finding a dash switch for the saddle tanks. And I gave up trying to find a replacement seal kit for my steering box. I scavenge scrapyards as much as catalog shop, for my C-10.

I can also recommend classicindustries.com, I've used them and LMC for at least 15yrs. Never had a bad experience with them.


/white paint hides a lot of wear and tear. There isn't a perfect panel on the whole thing.

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chilliwak

Expedition Leader
Thanks Chilliwak, I just checked out BDS springs on your recommendation. They seem like a great option. I will definitely check out your build thread!

We expo people are here to help. Lots of friendly people here with good info. Cheers, Chilli..:wings:
 

mccustomize

Explorer
Wow, mccustomize, I am envious of your fabrication skills! I just read your whole build thread, very impressive. I read your trip report for the Ozarks Challenge, as well. I live in Fayetteville and I was supposed to be the navigator for a team in 2015 (I think?) but a newborn and grad school prevented it. I know how tight those trails are, though, impressive work.

Thanks! Fayetteville is a beautiful little town, we enjoyed our time there. We had some pucker moments but staying cool and calm helped a lot.

There's a range of quality with LMC, but more often it's a choice of their stuff or nothing. GM dealers don't even stock the unique items for these trucks anymore. Just try finding a dash switch for the saddle tanks. And I gave up trying to find a replacement seal kit for my steering box. I scavenge scrapyards as much as catalog shop, for my C-10.

I can also recommend classicindustries.com, I've used them and LMC for at least 15yrs. Never had a bad experience with them.


/white paint hides a lot of wear and tear. There isn't a perfect panel on the whole thing.

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This one?
http://www.ebay.com/itm/Fuel-Gas-Ta...-Chevy-GMC-C-K-R-V-Pickup-Truck-/110741554180
 

vgreen

Putting the G in RGB
Hmm... I need to go pull some switches out of that brown cab before it goes to the scrap yard!

So pulled the rear diff cover off yesterday to find out what gears it has and check the general condition.

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No big metal chunk or even shavings, but it was pretty sludgey at the bottom of the case. I don't really know what that means.

Unfortunately, the gears are 3.42s, if I am reading this right:

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That means 12 teeth on the pinion and 41 on the ring gear, right? That works out to 41/12 = 3.4167.

I was hoping for 4.10s, I think they would pair well with 33s, the 1:1 cruise gear, and my intended uses. The sm465 I think will make the 3.42s livable for most of what the truck will do. I would like to regear to 4.10s in the future though.I was also hoping for a traction adder of some sort, but the diff is open. On the bright side, if I add a traction-adder to the rear, I think that same unit should work with 4.10s as well (at least with Detriot Lockers and True Tracs, that seems to be the case).
 

mccustomize

Explorer
I think you'll find the 3.42s not bad at all in low range with 33s, that SM465 has a pretty deep first gear. Any case the 3.42s and four speed should make cruising speed much nicer at 65-70
 

vgreen

Putting the G in RGB
I think you'll find the 3.42s not bad at all in low range with 33s, that SM465 has a pretty deep first gear. Any case the 3.42s and four speed should make cruising speed much nicer at 65-70

That's what my father-in-law said! At least it is not going to blow up at 70mph.I guess I was just excited for a silly crawl ratio. I think it to works out to 44:1 as it sits, which is respectable I think.

So I need a front spring hanger for the right rear spring (that's a confusing sentence). Mine is rusted through. I seem to be able to find them for reasonable prices for C-series trucks, but not K-series. I have only found one source for a 4wd hanger and it was over $100 (and that doesn't include hardware I believe). Any suggestions on where to look?
 
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