Having the same issue in my '85 after rebuilding the entire front suspension. I echo an earlier poster, pissed off after all that work is an understatement.

I had the guys at Blue Ridge Mercedes try to figure out the problem, no dice. Took it to the boys at Gran Turismo East and one of the techs thinks he narrowed the sound down to the guide rod or the upper control arm. Again, both are brand new.

Sounds like this is common. Is there a tried and true way to definitively diagnose the part making the noise? It's basically a popping sound as described that presents itself when braking heavy or turns that cause the car's weight to shift from side to side. Definitely makes a nice car sound and feel like a hooptie. Sound is coming from what seems like the firewall or just in front of it on the driver's side only. Makes a good case for the guide rod mount right there.