For forward or Rotary 4 post sheaves. This is the bushing installed on the ID of the sheave. There are various sizes of sheaves and bushings. Measure your shaft and housing and check that it matches the following.
Measure your shaft diameter, this is for 1-1/2 inch shafts.
Measure your housing size. This bushing is for a 1-3/4 inch diameter housing (press fit so the diameter will be fractionally smaller) and 3/4 inch deep (thick).