The bigger cars got the BUDD brake system in '67 and '68, also with 4 pistons per caliper.
They worked quite nice on my '67 Newport... right untill the unobtanium seals started leaking because of the rusty cylinders in the calipers.
The factory most likely found a cheaper to produce brake system and went with that later on.
Last sentence says it ALL , sorry RRR you are way off , you might know cars , but bean counters run what parts will be used , and they don't care if they are better just cheaper
