Rear brakes still locking up

No, hadn't thought about that. It seems to engage and disengage no problem.
The problem with the cables is they could be too short or adjusted too much causing the equalizer bar to spread the shoes just a little. I had this on my Cuda and drove me nuts, as brakes would adjust nicely and as they warmed up, the car would actually lock and pull right. Loosening the adjustment of the cable solved it.