Instead of rebuilding the worn out 4 speed transmission, why not convert to a 5 speed? Known for their high mileage capability with low maintenance, the 5 speed transmission has proven its dependability for over 20 years. S&S has developed a 4 to 5 speed conversion transmission case that includes an access door and all the necessary small pars. Simply add the 5 speed gears and shafts and you're ready to bolt it into your Big Twin 4 speed frame. Special features include transmission case cast from 356-T6 aluminum for superior strength and CNC machined for exact parts fitment. Access door is CNC machined from billet aluminum to eliminate flex and provide an exact fit. Compatible with 1970-later 4 speed chain drive style primary covers and power train. Can be used with aftermarket primary belt drive kit. Can be used with existing electric start components. Includes instructions with required parts list. Call 1-800-366-3464 for price.