**This thread may continue to develop as facts and documentation are discovered.**
I had the fortune of unknowingly recovering 2 prototype MTVs this past week from a location not too far from the old Stewart & Stevenson plant in Sealy, Texas. I'm doing the due diligence of documenting the vehicles for record keeping and my personal interest that I want to share with the MV community should they find it interesting. I encourage observation and discussion in this thread.
These two MTVs are now referred to as an M1084 and M1088 by current military documents. Data plates, numbers, etc are simply not on the vehicles due to their earlier production year (pre-contract) or are missing but they will be referred to their model numbers for ease of discussion. Both trucks are technically pre-production prototypes and not "proof of concepts” by definition as most major components remained the same to the production phase. Other changes were made but overall the functionality of the vehicles remained the same. Now that all that is out of the way..
These are 2 of 5 known prototypes released directly from Stewart & Stevenson before they were awarded the Army contract. The M1084 has no data plate in the cab but the rear crane is dated 92' as are the axles so it’s assumed to be of the same year. The M1088 has a data plate but is unstamped on year and so far no dates have been found. Each truck was either donated to or purchased by a VFD where they saw limited service and sat for years until recovered.
The M1084's main components were largely unchanged and made it into production. The cab, crane with outriggers, bed, and power train are the same as our contract made FMTVs with the exception of the axles being stamped "Rockwell International'" instead of Meritor that we all know today. The ratio is still 3.90 with the 2:1 hubs and looks complete unchanged without opening and confirming. Wheelbase is the same as a M1084 (I have one to directly compare). The transmission/transfer case is still an Allison 3070 wtecII like our first contract produced units as well. The engine is a Cat 3116 but the tag is partially unstamped or faded. The block serial doesn't come up in Caterpillar's online database either. Horsepower rating is currently unknown. The engine is largely unchanged except for more solid piping in some areas in place of flexible tubing.