Hello, Tom,
If you have a 1954 1/2 ton truck with an enclosed driveshaft, you can put in the 3.55 Ring & Pinion set (and all new seals/bearing/bushings - complete sets are readily available). I think that MotherTrucker sells the R&P, and, several vendors sell the complete parts kit.
With my modern 16" radial tires (on original 1954 16" wheels), and my 1960 261, I can cruise all day at 60+ MPH. I won't post the highest speed I have I have reached.
I have original-style brakes, front-end parts, and, steering. All are adjusted per the Shop Manual.
This set-up looks completely original/natural.
I have a 1960 261 - I think it has "precision" bearings - no shims. Does your 1954 engine need to be checked for possibly needed shims?
Best Regards,
Tim
