['ol Pinion head]

With decently thick used factory rotors, one can usually do this swap with factory mid '68-70 Bonneville-Excutive-Catalina single piston disc brakes for under $500-550. Several years ago, could do it for under $350, but most today, are having to get the brake boosters rebuilt & having to pay more for thick rotor used changeovers.

The disc spindles are same for '67-70 big Pontiacs. Caliper brackets should be different between 4 piston & single piston caliper. Good place to find needed parts is on Bonne & Exec wagons built mid '68 through '70. '67 & early '68 set-ups will use 4 piston disc brakes...expensive to rebuild & calipers can often leak even after being sleeved & rebuilt. BTW, late '60's through '70 model BIG Old, Buick, & Chevy set-up are all different & different from each other, in other words, no luck swapping on other divisional spindles & rotors. Good luck.