When I was going through LANCE Missile Officer training we had those and were told they were part of the MTOE for a firing platoon. Fortunately, by the time I got to a unit, the US Govt needed to bail out Chrysler Corp. so we were given Dodge pickups instead as an M-880. It was a maintenance nightmare due the brand new concept of the electronic ignition. We learned to carry a replacement ignition module for a quick change-over when it crapped out.
That's pretty funny.(But true).
After I got out of the Army, I worked as a civilian at APG. During one of the oil embargoes in the 80s when gas was $3.00+ per gallon, it seemed that all the GSA trucks suddenly appeared with big block V-8s.
My guess is they couldn't sell them in the civilian market so they foisted 'em off on the Government.