503 is a 1986 Chevy 4x4 5/4 ton (military designation M1008 CUCV). This truck is essentially a super heavy-duty version of the civilian 3/4 ton, placed into service in March, 1999.
It didn't run when got it, but we acquired a complete replacement engine from Forestry. One of our volunteers installed it, then off it went to another volunteer's house, where he and yet another volunteer went through the entire bottom end. This truck has been completely mechanically refurbished, and should serve us well for many years.

We rigged it up very similar to The Original Brush 1 with the big honkin' tires and a home-made skid unit consisting of a 200-gallon tank, electric hose reel, and 5-HP Gorman-Rupp high pressure pump.
We've seen other area fire departments put 300 gallons or more on these sturdy little trucks, but this one is pretty nimble with 200 gallons, we don't get stuck as much, and we still have some springs left.