As far as I know, Pontiac went with the 305 because of the death of the Pontiac V8 in 1981 and the close similarities between Pontiac and Chevy. Had a 305 in my '85 Parisienne, great engine! I know the Olds V8s survived long enough into the 80's and stuck with Buick and Olds, why Cadillac ever ended up with the 307 is beyond me.