A friend of mine here in England has a US import Winnebago from the early 70’s with the 340 Dodge engine in it. The engine itself is fine, but he gets really bad (as in 9mpg!) economy and would like to swap it for a diesel. So the question is - is there a diesel engine from Mopar or anybody else that would be a ‘drop in’ replacement? And even if there is an engine that would bolt up to the current automatic transmission, would this be a good idea, so should he be looking for engine/tranny combinations?
I can’t say I’ve heard of any Mopar diesels that would interchange. If there are, I don’t believe the transmission is a concern. However, it will be necessary to make some modifications to the fuel delivery system (proper filter, etc.) and electrical system (larger capacity battery and battery cables).
I don’t know if Chrysler ever made its own diesels or not; modern Ram pickups use a diesel engine made by Cummins.
That motor home probably sits on some sort of standard-issue chassis. A good starting point would be to find out what chassis it is, and then find out if that particular chassis was available with a diesel engine. If it did, try to find a diesel model in a junkyard—you can record how everything is supposed to go, and get brackets, wiring harnesses, and so forth.
I’m also guessing that if fuel cost is the only concern, this swap is likely not going to be worth it. You’ll have to figure how much money he’d save, based on the total miles driven, the cost of diesel versus gas, the increase in MPG with the diesel engine, and the cost of the swap itself.
For a (very) rough comparison, I used to drive tow trucks–mostly Fords–and I’d occasionally record the fuel mileage. With Boston traffic, my heavy foot, and a car on the hook some of the time, this is what I remember getting:
1992 Ford F-350 4x4, non-turbo 7.3-liter International diesel, 5-speed manual transmission: 10MPG
1997 (same body as '92) F-350 4x4, 7.5-liter (460ci) big-block gas V8, 4-speed automatic transmission: 6MPG (And the stupid thing only had one fuel tank–needed at least two fillups per shift!)