That U joint comes apart by pulling the small wire rings, then the bushings pull out.
That joint was never used on 1/2 tons originally.
I agree with Pre '68 Dave, that type of u-joint was never used on 1/2 tons originally.
I don't think you can get that type of u-joint to come apart while its still bolted to the tranny's main output shaft.
There doesn't look like there is enough room to slide the bearings over enough to remove them.The rear tranny housing is in the way.
The original 1/2 ton used cap screws with lock plates.illustration
That type of u-joint I think was used in 3/4 ton truck. Which has a partial enclosed torque tube and a open drive shaft.
Also, the 3/4 ton truck used a different (shorter) rear yoke. 1950 Shop manual (1/2 ton U-Joint)