Ratskin,
At least for 1962:
I am almost positive the spindle diameter is different between the 1/2 and 3/4 ton. The 3/4 ton is ~1.5" dia and the 1/2 is something like 1.3".
I just bought a set of lower ball joints (again 62). They were sold as "1/2 ton only", but are the same size as the 3/4 ton I removed.