It's been awhile since I have been on the site. I am in the process of installing a Cummins 8.3 in my "81" MCC. 8.2 DD is out and 8.3 is partially in. The engine is a mechanical 310 HP with an Allison MT 643. I anticip;ate I will have to modify the rear shroud. Any input would be appreciated.

Engine direction rotation?

I would hate to think that you would be the proud owner of the "World's fastest" coach running in reverse.
It wouldn't work anyway, trans wouldn't allow it.
Along the same line...
Water pump and fan clutch direction?

I've done a couple of re-powers in a few trucks, none in a motorhome. The biggest issue with trucks is the fan shroud. Make sure it is very close and resist the temptation to hack away at the shroud.

Also keep in mind that a 6 cyl is longer then an 8 cyl. Everything else will be a learning experience.

Take plenty of pictures and post them. We might see something to add.

Have a look at ... www.expertdiesel.com/motorhome.htm
They are swapping a 3208 for a DD in somebody's Regency.

Whoops!! Got that backwards me thinks!

Don, Thanks for the input. The 3208 swap was moderately successful. Talked to him. He only lives 20 miles from me. He did not like the job Expert Diesel did for him. The shroud I was referring to was not the radiator shroud but the rear cap on the body. Getting closer. rigajake

Any photos?? more detail???