Andrews "final belt drive" transmission belt pulleys match the 1994 to present design with a 50% longer internal spline engagement length than the earlier design. For 1985 thru 1993 models Andrews pulleys are supplied with a spacer for correct fit. Kits for 1985 thru 1993 models are supplied with seals, spacer and new style lock ring included. Stock equipment on all 5 Speed Big Twins is a 32 tooth pulley. The 31 tooth pulley will allow quicker acceleration (3% more RPM), the 30 tooth pulley allows even quicker acceleration (6% more RPM), the 29 tooth pulley will allow the quickest acceleration (9% more RPM), while the 34 tooth pulley will reduce engine RPM with 6% for smoother cruising.
Note: Although 2000 and later models use a narrower (1 1/8" in stead of 1 1/2") final belt and rear pulley, the front pulley width has remained unchanged and will also fit Twin Cam models.