That roll pin is used for the C6 trans equipped trucks or vans. The E4OD equipped trucks or vans requires a drive dog with 3 very small allen screws in it. You MUST make sure you remove and install this drive dog correctly on the new pump. PLEASE.... Take a pic before you remove this from the old pump. then you have no guessing. If you install it incorrectly you will destroy the TPS the first time to go wide open throttle. Mel usually asks what kind of trans you have so he can make sure EVERY needed part is in the box with a new pump.