You are looking at the air conditioning compressor from a 55
Cadillac with 331 engine, pt# 5911781. Fits the following:
1955-56 Buick
1955-56 Cadillac
1955-56 Oldsmobile
1955-56 Chevy
1955-56 Pontiac
Clutch runs smooth and quite however I never got the compressor
to pump. Consider it a core for rebuild. The whole unit will clean up nicely.
