The diameter of the 540 pto pulley is smaller than the diameter of the engine drive pulley. I can't remember off hand what the pto pulley diameter is right now, but something tells me, when the pto pulley is slide into the engine drive pulley, you can see about a 1/2" of engine drive pulley around the perimeter of the pto pulley. My guy didn't have any troubles making the pto pulley, however it did take a couple tries getting the angle cut right for the belt depth and sizing. If I remember correctly, I think I was selling them for $25.00 each including the locking pin.