2008 Gmc Savana AWD to 4x4 conversion

[jonnypage]

Hey all. I have finally finished my conversion. I took some photos to help others along the way . I used this thread for some of it https://expeditionportal.com/forum/threads/chevrolet-express-van-awd-to-4x4-conversion.52911/

But I did a few things differently .
The donor vehicle was 2003 Silverado 1500 4x4 with a manual shift Transfercase (np261 LD) and the 4.8 is the vin( 1gcek19v03z120742 )
I used the shifter from this vehicle and heavily modified it to work as it originally mounts on the side of the trans tunnel and obviously it needs to mount on a flat surface for the van

The transfer case bolts up perfectly. Even down to the speed sensor with just enough clearance between the drain plug and the torsion bar cross member.
I have not used the front white plug as this is the display for which gear you are in. I May end up wiring this up to some sort of crude lighting system so I can see which gear I am in but so far it doesn't seem worth while.
I fully rebuilt the transfer case and installed the Pump rub kit to prevent any further damage.
I had new drive shafts made up Re using the old front drive shaft - Transfer case yoke
This is what the drive shaft shop has on the invoice. These numbers are to be used as a guide only and I take no responsibility for their accuracy
Front shaft
2x SKU: N3R-28-307 Weld Yoke
2x SKU: 5-795X U joint kit

Rear shaft
2x SKU:3-28-427 Drive Shaft Tube Weld Yoke
2x SKU:5-1350X U joint
1x 3-3-5551X Slip Yoke

Drivability is Great. In 2wd there is noticeably less biding in tight parking lot type manoeuvring. No gear shifting issues
In 4wd it acts just like it used to in AWD with more binding when doing turns on pavement ( just like any other 4x4 vehicle with no AWD) No gear shifting issues.
In 4wd low it drives great also. This is the sole reason I did this swap . Low range. We go off road a lot. Nothing crazy but I am a firm believer in slow and steady. We air down and crawl up any steeps in low range. The shifting as mentioned in the original thread by zuren Due to the output shaft being significantly lower ( low range) Does not happen automatically. This is solved by starting it first then shifting to second manually and then thirds. They maybe a way of reprogramming the ECU But I don't see the need for that.

 

[hopalongkid]

This is great! I just replaced my transfer case in an AWD Savana, and heavily debated this route. Ultimately, I opted for a rebuild AWD transfer case since there was so little out there on the swap. (I had read Zuren's thread, and seen some chatter on Facebook)

Glad to know it worked out, and will likely go this route if I ever have to do the job again.

 

[Herbie]

Looks great. I'm glad this is still "a thing", as the easy conversion of GMC/Chevy vans was one of the reasons I chose mine.

As I mentioned in Zuren's thread, the solution for the shifting issue is most likely just finding the right 4LO input pin on the ECU and rigging up a switch to short it to ground when you're in that mode. Here's a write up on how I did it on my Astro van:

Retro Post: AWD to 4WD Conversion with NP233 Transfer Case

Another Retro Post. This time I'm documenting converting the Astro from All Wheel Drive (AWD) to proper Four Wheel Drive (4WD) with a 2-...

herbiesworld.blogspot.com

Obviously the ECUs are different Savana vs. Astro, but if GM followed their usual pattern, I bet there's a lot in common between the Savana ECU and the donor Silverado. A little time spent poking at the factory wiring diagrams would be worthwhile.

 

[Herbie]

What engine in your Savana? I bet we could track down a 4x4 truck with the same Engine, and thus the same PCM.

You're looking for this type of pin. (This is for a 2003 5.3 PCM, so likely not the same pin on your ECU...)