replacing upper control arm

Well here is yet another twist to the upper control arm saga.

A-body UCA:

Disk Brakes up to 12-1-75 and after 3402702/703

Drum Brakes all 3722460/461

>Disc Brakes HD after 12-1-75 3722460/461

http://www.slantsix.org/forum/viewtopic.php?t=38363&sid=093192987cf0eb4ee706df262e29546f

If this is correct they beefed up the UCA on the drum brakes in 1974 and changed it over to be used on a HD disc after 12-1-75.