I bought and used a 1955 Dodge D500 17 flat bed truck to haul fire wood and logs for around 5 yrs and then had my Father in Law put a car hauling ramp on it to haul my cars.
That motor was a industrial Desoto or Chrysler in line flat head six that was either 254 C.I. or 263 C.I., I never took the time to make sure which motor it had in it

It had a freeze crack from the front of the driver side on the bottom of the water jacket all the way back to the rear of the block I would drain it in the winter and put water in it when I wanted to use it
It was a six volt system originally and it had a truck 4 speed with a vacuum operated two speed rear end, the speedometer didn't work worth a hoot so I never knew how fast I was going, I knew how slow I was going by the amount of people lined up behind me waiting to pass going up hill on two lanes roads back then in the Mojave Desert
I ended up putting a stock 1957 392 Hemi in it around 1978 or so and converting it to 12 Volts, that ended up being the best thing I could have done for that truck
I pass many other racers towing trailer on the flats and uphill going to the races with that swap
I've own three other car hauler trucks since then and now use a 24 Ft Pace enclosed trailer and tow it with my 2006 Ram 3500 l4 door long bed 4x4
Lots of ways to get the job done
End of ragging on slant sixes