I have never been able to find a definitive answer as to the difference in M20 trans. options for RPO L48,L34,L35 & lM1(3950356) vs. Z28&L78(3946797). I reference the AIM M20 A1. Hoping someone will educate me as to How to ID one from other when tag on side cover is missing. Somewhere I thought I read it had to do with speedo gear, but that may explain the Z rear axle, and not L78.... see my post regarding "SS 396 rear axle ratios" below. I hate to post if this has been covered already, but I pour over these posts daily and do a lot of searching and cannot find the correct information. I promise, I will buy Jerry's book someday, but until then? I guess, I too would like to be regarded as an "expert" someday on at least 69 Big Block cars. Thanks again CRG, Bentley B.
Yes, the main difference between all the Muncie M20 transmissions is the speedometer gearing, which depends on the rear axle ratio and the size of the tires. For instance, a 3.31 axle ratio with F70-14 tires wouldn't use the same speedo gear as, say a 3.73 axle with E70-15 tires. The MPH would be off.
Ed
see post on axle ratios,thanks.