Hello, Thad
"I’ve found a 1951 stake bed 3/4 ton rust free. It still has the long bed step side running boards."
There was one size 3/4 ton bed/frame (and another different size 1/2 ton bed/frame; and, a third size 1 ton bed).
I think they all had different running boards.
There were two running boards available on a 3/4 ton:
75 3/4" long (standard)
40 3/4" long (optional on both 3/4 ton and 1 ton)
87 1/2" long was used on 1 ton panel and pickup
In order to use the 1/2 ton running board on your 3/4 ton, you'd have to determine if the mounting brackets on your truck will work.
Maybe someone reading this will know.
"It’s a 4 speed. Any guesses on rear gear ratio?"
Here are rear end specs.Here are the transmission gears ratios.
