Used GM pulley. This is GM# 3788472 CO. This is a 4-bolt, single groove water pump pulley, approx 7 1/8" outside diameter, 5/8" center pilot, and approx. 2 5/8" deep (when measured on a table). Universal GM applications, mostly in the 60's for non-A/C and non-power steering applications.
The item in the photo is the exact item being sold.