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Hurst includes reproduction GM "621" bellhousings with its kits, but set us up with an optional Quick Time SFI unit. Before installing the clutch, Jarvis tightened the bellhousing to spec and attached a magnetic dial indicator to the crank to check for runout. Hurst recommends a maximum of 0.005 inch of runout, which ensures that the input shaft of the trans will align properly in relation to the crankshaft. As it turned out, the bellhousing was positioned too far toward the 8 o'clock position, so it was moved closer to the 2 o'clock position using offset dowel pins. Jarvis attributes the initial misalignment to poor manufacturing tolerances when the Olds block was originally cast.