Another neat, simple, winning solution from Seals-ItNo dirt keeps Torque-Ball free!There is no contact between seal and crankshaft, so there is no added dragDoes not interfere with fast engine removalRubber seal is bonded by a patented process to precision machined anodized aluminum - NOTE: At the present time, the only engine style these fit is the Chevrolet crankshaft flange bolt pattern of 3. 580" diameter, which is the most common in use at this time. Note that this is the flange pattern used on the two piece oil seal crankshafts. There may be some groups that require the use of "stock" crankshafts. One piece rear main seals used after 1986 have crankshafts with a 3. 00" bolt pattern. The "cup" will not fit these. Since the vast majority of aftermarket crankshafts and blocks use the 2 piece seal style crankshaft, there are currently no plans to offer a cup for the 3. 00" parts.Pit Stop USA offers Seals-It Torque Ball Seal Assembly - For MPD Style Housing TBS1A-07 at low everyday prices. Be sure to check out all of our products from Seals-It including Seals-It Torque Ball Housing Seals.