that goes between the flywheel and the block, as well as another one that goes between the flywheel and the tranny bellhousing. If you left either of these out or put them in the wrong position, it could cause the bellhousing not to seat squarely against the block, which could put your clutch>flywheel engagement at an angle. That could cause problems as the engine and tranny, to a lesser degree, begin to warm up and expand from the heat. That's all I can think of at this point, assuming that you also already adjusted the clutch pedal as described in the TECH article.
