Mt54,
Which 1954 truck specs says 3.70 rear?
Most likely that is a miss-type of 3.90 standard 1/2 ton rear in 1954 trucks (there was no optional rear in 1954)?
I agree with Don, I wouldn't change from a 3.70, but I did change from a 3.90 to the 3.55 (31.5" diameter radials). I can cruise all day at 65, stopping every 150-180 miles for gas.
