[Gasoline Fumes]

Originally Posted by northboundtrain

I did this same conversion several years ago. It can still cost a lot of money, even if you already have the engine. You'll need a different flywheel, starter, exhaust, batteries, glow plug relay, etc., etc. And depending on the condition of the engine, you may need to replace/rebuild things like the injectors, injection pump ($$$), etc. IIRC, the diesel engine has oil cooler lines, so you may need a new radiator too. I remember it nickle and dimed me to the tune of several thousand dollars by the time it was all finished. Perhaps you have more parts than I did to start with, but don't underestimate the cost of all the components to get the vehicle moving.
Then you'll have to figure out how to register it, which may or may not be an issue where you live.
And finally, the old GM diesel is just not a great engine. I saw a very modest mpg increase, and the power for towing or plowing just isn't there. You probably won't ever come close to recouping the cost of the conversion in fuel savings, particularly since you don't plan to drive it a lot.
For a lot less, you could probably tune up and modify the 350 to make more power and be more efficient (headers, free-flowing exhaust, carb rebuild, engine freshen up, towing/mileage cam, etc). It would crush the 6.2 for power and torque.
Then again, the 350 may be worn out and need re-boring, full valve and guide job, etc, but if it's really worth $500, then it should still have good compression and be within wear tolerances.
Anyhow, I'm in the process of freshening up the 350 in a '77 3/4 ton and doing the above-mentioned mods, so when I saw this post, I figured I'd chime in. Hope it helps.

Thanks for the advice. I'm actually very familiar with the 6.2L and its shortcomings, it's coming out of an old rusty '83 GMC that I've had for 8 years. Plenty of power for plowing. And I've towed with it, so I know what to expect. Both engines are in good shape. I need to catch up on some maintenance on the 6.2L, but it has a recent injection pump and very good compression. I got really lucky and found the diesel flywheel, clutch and an external oil cooler with new lines in a junkyard Chevy P30 stepvan. My donor truck is an auto, so finding those parts saved me hundreds of dollars. I basically have everything to drop it in.

The 1980 is a heavy-duty 8,600 lb truck with no catalytic converters. Basically emissions exempt in NY. I can put any engine I want in it. I'd go with a 4-cyl turbodiesel if they weren't so expensive. If I wasn't going diesel, I'd put a 6-cyl gas engine in it and get the 6.2L power and mileage.

The 350 came with headers and other performance goodies. But it got around 7 MPG towing and I have to pay whatever the gas stations charge for fuel. The diesel will run on free WVO. And I like the way the 6.2L sounds.