My son and I put a 4BTA from a bread truck in his YJ Jeep rockcrawler and it came from a GM chassis so it had the flywheel / bellhousing / rear engine housing for a GM manual on it. An SM 465 in this case which we modded to a 4wd tail and it works great. All the configuration parts are bolt on for a Cummins and swap between a 4B and 6B. Should be able to find them in a truck junkyard or Craigslist.
Peninsular has been around for a while and doing 6.5 engines for 15 + years I know of, so they must have a decent product. Have fun