Can anyone tell me if there is a direct swap available, and if not, what are my options.
1955-1959 chevy 1/2 ton rears (Eaton HO33) are as close to a direct swap as possible. However the rear parking brake cables will not match up to the chevy rear. The good news is you can get new parking brake cables to fit the chevy rear. The spicer cables might even be able to fetch you a buck or 2 as these are not readily available in the aftermarket.
Just out of curiosity, what transmission are you running with the spicer? Reason I ask is the maintenance manual I have states the spicer has a 3.08 ratio when used behind a 3 speed transmission. I believe there is a 3.92 gear available when the spicer was used in a "posi" aplication. Anyway, chevy 1/2 rears mentioned above are usually a 3.90 ratio, so your truck might drive differently.
Other options include using a 12 bolt rear from a 4x4 from 1960 to about 1970 something, and possibly later. These rears are about 62 inches wide wheel mount to wheel mount, and use the same parking brake setup as the earlier 1955-1959 chevy 1/2 ton rear. The 12 bolt has many more gear ratios and posi-tractions choices than the spicer 45 rear or the eaton HO33 rear. The spring perches usually need to be cut off and rewelded for proper pinion angle on these rears.
