Twice as many miles on the body/chassis has to be considered. What difference does it make having an engine that goes for X00k miles when the body only lasts X00K miles???
Do you need the added GVW of the 350? What is the actual difference in capacity?
I had an '82 E250 with a high GVW with a 5.9l carbureted engine. I ran a tree service so it pulled heavy trailers and chippers occasionally. It went to the junk yard with 245k miles on it. The body was shot! Needed complete brakes down to the hubs, tranny [it would have been #3], engine oil leaks.
In the end...mileage on the vehicle is key to me.
Tom
Sounds like whoever owned the tree service didn't maintain his junk. If it went to the junkyard needing brakes that bad, they didn't maintain the brakes, plain and simple. Bodies can be more difficult depending on where you live, but mechanical comes down to maintenance. They either did it, or they didn't, and it sounds like they didn't.
There's a fella leasing property from me that has a 2001-ish superduty with 400k on the clock that's done pretty much nothing but routine maintenance on his truck as far as the engine and other mechanical. He did have to replace the bed because it's a work truck and between that and Ohio winters it gave up the ghost.
The OP said they both appear to be in similar condition. Based on his limited info I'd take the 7.3 without hesitation, even if I had to rebuild the tranny in the deal.
I've owned or currently own just about every engine Ford has offered in the diesel configuration from the 7.3 idi to the 6.7. Same goes for the gas excepting the new ecoboost and the 6.2.
On the gas side of things IMO if all you need is a 5.4 you don't need anything heavier than 150 class, and it shouldn't be in anything heavier. The power doesn't compare to the 6.8 and the fuel mileage advantage, especially when it's in the bigger trucks, is questionable at best.
On the diesel side: The 7.3 anything doesn't hold a candle to the 6.0 and later when it comes to power/torque. It also doesn't hold a candle to them when it comes to repair costs. The 6.0 on can eat you alive with repair costs when something goes south. For the average Joe a modern diesel is a ticking time bomb that they will absolutely love until they get hit with the bill for their first out of warranty major repair. Ford repair cost for a failed High Pressure Fuel Pump on a 6.4ltr diesel is north of $10,000.00, depending on the dealer. Though cheaper by far, you won't do well enough at a quality independent to make the tears go away.
Unless you are towing really heavy, doing it a lot, and/or making money off your 6.x diesel, it isn't worth the risk.
The 7.3 is a whole different story. It's plenty powerful enough for the average hauler. It's reliable and durable, and fairly inexpensive to repair when something goes south. You can buy a complete new Ford long block for less money than it costs to fix that aforementioned High Pressure Fuel Pump on the 6.4.
I have a 7.3 idi. A 6.0 and a 6.7. I've owned a few 5.4 in a truck and SUV config, and 3 different 6.8s the same way, though none of those currently. If I were to toss one from each category it would be the 5.4 and the 6.0. One just doesn't compare to its gas counterparts, and the other is a bit delicate in its factory config, and is expensive to fix when it breaks down, or expensive to fix in an attempt to make sure it doesn't break down.
Ok OP, you wanted reasons. There's a few. All things being equal in the feature/condition dept, I'll take that 7.3 every time.
