Here is the first one:
From TM 9-2320-209-20 dated 7 april 1965 on page 20: "The M109, M109A1, M109C, and M109D are gasoline engine models with minor differences. The M109A2 is the same as the M109, except that it has a multifuel engine." And: " Instrument repair shop vans M185, M185A1, and...