This includes some interesting historical info about why no M-151s were built to be APUs. The question seems to be, was this a motorpool modification or someone’s backyard customization.
https://newhaven.craigslist.org/cto/d/1965-m151a1-mutt-apu-ford/6654432656.html
“Not much is known about the history of this little MUTT except that it was an original Ford built M151A1, produced in 1965.
On the back is a rather elaborate electrical generation set up, that includes replacement of the transmission with another generator unit. Power comes from what is believed to be a Continental flat head 4 cyl. The vehicle moves by an Autronic Unit transfer gear set-up that hangs off the front of the small “jeep”. A shaft coming off the front of the crank runs a chain that drives the “transfer case” that powers the front axle.
“Following the introduction of the M151-series, the US Army’s monthly “PS” magazine warned units that they should not turn in their M38 welder-equipped vehicles for M151 trucks, because “there is no authorized mobile arc welder for the M151-series 1/4-ton truck.” (See PS Magazine issue 124 page-65.)
There was a simple reason for this. The M38 and M38A1 like their predecessors the Willys MB and Ford GPW and some early CJ-vehicles, had a transfer gearbox which could be adapted to drive a pulley for accessories. The M151-series didn’t. Adapting the M151 to drive an accessory was virtually impossible because of the transmission-transfer design.”
The above, written to me by a MUTT Guru, explains why A) I feel it may be a Continental engine, which were used in many industrial power situations, and B) Why this is most probably not an official US Gov’t issued M151A1 Variant. With the flathead 4, adapted here to power the various generators on the MUTT, and the ingenuous way it was made to work together and create, it can be surmised that this complex set-up was designed on a military base, to stay on base, as the ground clearance is not enough for this vehicle to be driven easily on roads, never-mind in any kind of off highway travel. Additionally, there is no official documentation of any MUTT APU’s however, it was common place for GI’s to use their skills and resourcefulness to create machinery to do a particular job.
It may not be official, but it was very probably used in the military for military purposes, either to power up airplanes or as a generator to power small camps/barracks and… you’d be the only one to show up at a military event with one of these.
This little truck is rather rough but it is felt she deserves to be brought back and shown as the work of GI ingenuity that she is.
Asking price by the owner is $2000.”