I feel your pain making this decision. The following are some brain spasms to give you and idea.
Typical issues when keeping stock drive shaft and rear axle - Torque Tube:
1.) 2X Bushing replacement (Oakie Bushing easiest) & ball housing gasket. Not fun to do. Use GM service manual. Experience definitely helps. Will still leak a bit (nature of the beast). Everybody puts a drip mat underneath an original Stovebolt.
2.) 1954 rear axle ratio usually 4.11-to-1 or 3.90-to-1. Your 235 engine will high RPM at 50/60 mph (nature of the beast). The engine will start dropping torque after 2500 RPM. It's a personal taste but around 2100 RPM is highway cruising speed. See Deve's website for 3.55 highway gear conversion. This is doable but then good experience is helpful to do this properly. Getting the gearset to mesh well is tricky. Search Mothertrucker for one source to purchase the gearset. Hopefully you don't have to replace $$$ bearings but the seals may need replacing. Use a handheld GPS with a MPH function if you speedometer is on the blink or not accurate.
Drive shaft and rear axle replacement - Conventional:
1.) 1954 1/2 ton width inside flange-to-flange 60" to 62" but measure yourself.
2.) Chevy trucks beginning 1955 2nd half year, rear axle is wider. Appearance issue with tires to fender opening.
3.) Old school replacement options. Early Camaro, Nova, Chevy rear axles. These axles are hard to find and may be worn badly (may be money pit).
4.) Search 9" F@&d for new parts solution. $$$.
5.) Typically you end up with a rear 5 bolt wheel pattern and may wish to convert front axle to 5 or buy 6 bolt rear axle shafts.
6.) You can reuse your old leaf springs but may need to fashion or weld-in new axle saddles (search the forum).
Transmission:
1.) Old school is Saginaw 3 speed or 4 speed (maybe your 230/250 transmission). Synchronized first gear desirable. Final gear ratio is 1-to-1. First gear ratio options (2.85, 2.54, 3.11, 3.50, count rings on input shaft). 1st gear ratio X rear axle ratio to obtain about 9 or 9.5. Too low (example 2.54 X 2.73 = 6.9), ride clutch to get truck moving. Too high (example 3.11 X 4.11 = 12.9), jack rabbit. Calculation to determine engine RPM. RPM = (MPH X transmission final ratio X rear axle ratio X 336) / tire height. There are tire websites that have tire size calculators to make number crunching easier.
2.) Current manual transmission trend is S10 5 speed. Sorry, you will have to search for info but it's easy to find.
