Hey I just went through ALL OF THIS and WHAT A HEADACHE! I located a BRAND NEW MATCHED set of speedo gears for a 48 passenger Chevy to put into my original torque tube '54 three-on-the-tree Muncie. The fellow I got it from is CHAROB Industries in the San Fernando Valley and he (Charles or "Chuck")has one more left, brand new matched set NOS, which is what you need. What I found was on both my old trucks the drive gear on the tranny output shaft was worn. Had to rebuild the entire tranny. At the moment I do not have his phone number but his address is 11267 San Fernando Rd. San Fernando Ca. 91340. The speedo works perfectly well now(despite being off just a tad!) and the old truck finally clocked its first mileage in 23 years. These NOS matched gears are getting REALLY HARD to find so I wouldn't wait to procure them. Took me weeks to locate them myself and trips to all my local speedo shops.