65 a/c compressor 5" and 5-3/4"
Which size came in 65's, I don't have a compressor to measure.
Local parts store gives me a 5' or a 5-3/4" clutch size. sigle groove.

Thanks
Jim

65 chevelle w 283, powerglide, the outside hub (closest to the radiator) is 4 1/8" diameter (maybe 4 3/16"). The next 'shelf', the actual piece that spins with the pulley is 4 3/4" diameter. The pulley, single groove is 5 1/2 inches in diameter. This is the original compressor to my car.