Does anyone know what year these spindles are from

They have the right look for an A-Body spindle. Pretty sure the F-Body spindles look lighter. Might look up Ehrenberg's disk brake swap stuff, he has pictures in it showing some measurements for the A-Body spindles. I saved the picture, but don't have time to track it down and link it for you, sorry.

From the picture:

Stub should be 5.5" long from the base to the end of threads.
Stub should be 1.375" in diameter where the inner bearing rides.
Spindle should be 4.5625" tall from the center of the stub to the bottom of the spindle, on the inside, where the upper balljoint nut would be.