Years back I purchased a mechanical 6bt to install in a B3500 looked fairly straight forward.
Well a gentleman in Missouri has done that swap in a 94B350 and I was fortunate to speak to him before I began. First he loves the van but says he would never do it again. He mentions the small but time consuming issues like converting the fuel system, engine compartment wiring and in later vans getting the dash gages and hvac system to operate is small potatoes.

He is into a 1994 B350 in excess of 50k and it is no show van the most significant issues were the additional weight on the front end and heat. The exhaust took him three try too locate the turbo properly the first try melted his dash slightly while he was sitting in traffic. Vans engine compartments as we all know are hot in the summer imagine a turbo diesel with those exhaust gas temps. Not a easy problem to solve, I don't recall where he located the turbo but he did add quite a bit of heat shielding. The additional weight he dealt with by taking the spring weights of a Dodge Cummins 4500 (chassis body) and have a custom pair made along with upgrading everything he could in the front suspension, I believe he likes the current setup.

IMHO go with a Duramax as it will be enough work and relatively bolt in, best of luck if you make the plunge.

 

Or just buy this and be done with it...


Chevrolet Express 1 Owner 197K Solid Southern Wagon C 60 Photos Rig | eBay

 

That interior brings back memories, but I don't want to go back to that. I'll just daydream about a little diesel and ways to make it work. It's beyond my resources, but I like the idea if it wasn't.

 

That ebay van is CLEAN!!!!

 

I know, it's tempting just for that reason! People down South are lucky. It's not too bad here, but there's so much water you won't find a van that clean here. Go East and the salt eats them alive.

 

Here is another, wouldn't mind having this one...


Chevrolet Express 1 Owner 164K HD Look Alloys Clean A Team Wagon | eBay

 

Another nice clean van but I have to agree with dberladyn that current vans are rugged as well and much more comfortable to drive. Also these older diesel G30s seem too hold their value, for those sums of money you can purchase a nice decade newer Express.

 

More comfortable yes... but that van's body will outlast any Express on the road, easier to repair, the paint won't fall off, and will get 24mpg. If I bought that I would put in some captains chairs, air springs on the front and some insulation... will be plenty comfortable. Wish I had a reason to buy it.

 

24mpg? Are you serious? If that's the case, I definitely bought the wrong van but... Anyways, you can't be right on that. I can't see GM making newer vans only to have them get half the mileage. The Savana/Express Diesel owners I talked with get the same kilometers out of a tank that I do with my 6.0L.

 

Ill stand corrected at 20mpg highway.