TCI GM Bellhousing Dowel Pins, .625 in. Diameter, 2.0 in. Length, Straight, GM, Pair Dowel Pin Offset (in): None Dowel Pin Length (in): 2.000 in. Dowel Pin Diameter (in): 0.625 in. Quantity: Sold as a pair. These extra-long dowel pins are a must for any application running a mid-mount plate to ensure that the transmission bellhousing is properly aligned with the engine.