I have one of those, it was built as a shelter carrier (S-788 and their kin) to be towed by Humvees. Military designation (if it ever had one) is unknown.
It was made by Laguna Industries. That company had serious management problems at the end, and went defunct some years back after having all their government contracts cancelled for failure to produce on schedule. Their products were good when they were producing them.
A search for Laguna Industries now takes you to a shed behind a house on a reservation outside of Albuquerque. I tried every contact number and email address I could find some years ago when I got my trailer, everything was disconnected or otherwise a dead end.
There were very few made, I know of only three including yours, though mine has T0006 painted on it.
My understanding is that they were prototypes or pre-production units made to compete with the Silver Eagle FTT, but the FTT won that game. This is what I was told, I have no documentation to prove it.
Mine is still in it's original paint, and I cannot see that it ever had any data tags attached. I only know it is from Laguna because it has their cage code stamped on almost all the parts (which is how I also know it is in it's factory paint
).
Yours doesn't have it, but the other two have a box at the front of the deck which contains two batteries, a diesel tank (both are to run the shelter-mounted generator) , and the electric brake controller with all its ancillary bits. Yours also looks like it is missing the small bumperettes from the rear.
I don't know your plans for it, but judging by the number of people who have tried to buy mine from me to put a shelter on, they are sought after for that purpose!
I have pictures of the original shelter mounting equipment if yours is missing it, so you'd know what to look for.
Mine now has an S-788 mounted and I'm slowly finishing the restoration on it.
I don't have a Humvee, I pull it with my M1028A2.
Cheers