I wish I had more solid proof than repeating what I was told on this topic but I had the pleasure of speaking to Steven Jonna and Tom (forgot last name) from AM General back in mid-2018, Tom later stopped by to pick my motorpool for Project Brutus and we got to talking. I asked about a variety of things from the M35A3 program to the 5TTR/MTVR program and this was on the list due to its unique nature. Don't get him started on M35A3 fiberglass hoods.. just please.
From what I was told by Tom, take it with a grain of salt, was that the Army was looking to step away from manual transmissions all together. This was the main driving force to part with the M809 and older series 5 tons. AM General was pushing to refub the fleet but it was a hard line in the sand that they eventually accepted and went back to design the M939 series trucks. I don't have any info why they didn't implement the CTIS from the start of the M939 and waited until the A2 came out (yes yes BMY). If anyone has info there please share for my knowledge. From Tom's knowledge there was only 1 truck made and that was it. It was made to see that it could be done but also to make media to sell it to the military. He mentioned being part of the surf photo shoot and that it was a cold day.
Tom was an interesting guy and a "lifer" for AM General and that extended to his father that worked on the M35A2s back when they were new too. I knew my time talking to him was short so my questions had to be specific and interesting for him to answer so my mind was an audio tape during the chat. It wasn't until I got home to decompress, think, and scribble notes down in a word document that they cast some light on old intriguing thoughts like this. Since his visit was discrete due to the nature of his mission I wasn't able to get a photo or anything beyond repeating what I was told.
If anyone has evidence for or against this please share it. It's only 1 man's word and I like to know more. Odds are the truck is long gone as Tom too mentioned AM General disposed of unsuccessful projects. They do have crates of fiberglass hoods for the M35A3 but they'll never see the light of day..