Replacing a gas engine with a diesel

TauneZ wrote:
I have been looking at full-timing in an RV for a while and have finally found an affordable one that is in surprisingly good shape. The only problem is, I know I really want a Diesel engine and this one runs on gasoline. (No talking me out of diesel.)
I wish I knew a bit more about mechanics. I wasn't able to get the dimensions of the current engine (it is a craigslist ad). I've already asked so many questions and I don't want to bother the owner too much if I'm not 100% sold.
I was wondering if anyone knows what dimensions of engine would fit in a 1972 Dodge Lazy Daze chassis. I would hope it has space for about 400 in³, but I'd like to have more specific measurements.
Would a 6.7L Ford Power Stoke (2010) even begin to fit and be compatible, do I need to go with a smaller engine?
Does anyone know how much it would cost to replace the engine?
Sorry for all these questions, I'm a complete newbie when it comes to RVs.

We bought an Isuzu I6 diesel engine for our newly purchased '78 Vogue Class A motorhome in 1980, and had it installed after pulling the Chrysler 440 c.i. V8 yanked out. It fit and worked perfectly for over 10-years and 125K miles with no problems at all. The used 440 brought $500, and the Isuzu I6 with install was $6K.

I would probably do an Isuzu I4 diesel engine install in the Dodge van you're describing. Your MPG will almost double from what the gasser is giving you.