Brake spindle ID help

[pbro]

I purchased locally some brake spindles of which I plan to use on a disc conversion with my 69 gmc drum. Before I order ball joints and tie rods, can someone tell me if I truly have 71-72 spindles?

Inner casting numbers are b212 3989487Ih8 and outer numbers 461 gm 9n & rh7 8888482 l221 (last set are hard to read).

Rotors were 1.25” wide.

Any help identifying the years of these spindles is greatly appreciated.