About a year and a half ago I put the "B" body spindles on my 78 EC.I also used the "B" calipers, Poleposition uppercontrol arms, LE1 rotors, replaced all the hard and soft lines and the combination valve. The only thing not replaced yet is the master cylinder. The brakes worked fine for the first 8 months and then they started to pulsate in heavy braking. I had them turned, but now they are pulsating again and pull to the left slightly. Is the Master cylinder the problem or could it be something else?
Thanks for any help.

It sounds like warped brake rotors is the problem.