I'm a huge fan of the old M37s, and back in the mid 90s I was involved in helping a friend convert his M37 Ambulance into a camper and comm wagon. One day soon after the grand finish in late June and its maiden "voyage" on field day, his neighbor came home in a rental vehicle with a wrecker towing his obviously badly wrecked '92 Dodge W350 with the Cummins Diesel and a manual tranny. The neighbor wasn't hurt - the W350 was parked and struck by a runaway lumber yard forklift left across the street with the parking brake off.
A few days later, Ol' Bud offered the neighbor's insurance company a fair salvage price on the Dodge, and we spent the nights and weekends of the next 5 weeks putting the Cummins and its tranny in the M37, converting the fuel system to diesel, and the electrical to modern standards, and adding those luxury items such as power steering and more modern brakes. Lest the purists find fault in that, the M37 can be returned to original driveline, etc., with little work because the conversion pieces were fabricated or bought aftermarket to accommodate the original equipment just for that reason. He still has it, I still want it, and we can't come to an agreement that will let me take it home for my own........oh, well......
Congrats on the work and success!