Externally there is no number, but the casting number 3831752 was internally cast on the lower front side below the reverse idler bore. He rebuilds them using all new gears and internal components. An extra heavy duty close-ratio version M-22 was also offered on many of the big-block high-performance models. We use and offer a complete line of high quality new parts in our transmissions and for sale to the do it yourself re-builder. West tells people to think of a transmission in terms of levers. A Muncie differs from a Saginaw transmission in that its reverse lever is in the tail housing, not the side cover.
A shifter handle has a specific bend to it. We also recommend installation of all parts by trained professionals with the proper tools and equipment. I spent a great deal of time sorting through their parts. With the introduction of the 3885010 case, the countershaft bore was increased to 1 inch. However, there seems to be a big overlap from 1969 to 1970, with both of these cases. You can identify the various M20, M21 and M22 transmissions by the input shaft.
Ratios of the M20, M21, M22 Muncie 4-speeds were produced in two different ratios wide-ratio M-20 and close-ratio M-21. Most of the core transmission case he buys now are dated. Torque upper 3 bolts and lower 3 bolts to specification. Transmissions are an essential part of hot rod builds. Check bushings for excessive wear by using a nar- gag: 73:5? This decodes to 1972 2 , March C , 25th, M21 B. The main internal differences in the 3 types of transmissions are listed in the parts below. A lot of people call him looking for a correct transmission.
The downside is it tends to make noise. People often get confused about what a casting number is. This is for a 1968 production car. This might have been a different alloy because its appearance is identical to the 3851325 case and it was to be used strictly with the new big-block 396 engine. I enjoy what I am doing. Gears are multiplier of torque.
Stamped serial numbers for all 1969 model year cases also included the year designator. If you take a few moments to study the gear chart for your transmission and rear end ratio combination you will see why this product is so popular. A serial number is stamped on all Muncie transmission cases. Muncie 4-speeds pretty much have a solid chronological order regarding the main case, retainer, midplate, and extension housing casting numbers. This Muncie main case carries specific factory coding. The Muncie reverse lever stud is in the extension housing, whereas the Saginaw has a third stud through the side cover for the reverse shift lever. The progression of the 10-spline input identification groove system.
These two milled 3864 cases have March 1965 assembly dates. Simply put, it is the number that is actually cast into the case when the molten aluminum is poured into the case mold. A later type bearing retainer is on the bottom, in the center. This is a page from an old factory 1967 Nova assembly manual showing three different part numbers for the M20 and one number for the M21. Coincidentally, March 1965 seems to be a time when the 396 engine started to migrate into more vehicles, such as Z16 Chevelles, Corvettes, and full-size Impalas. If you mix and match randomly, the length and shape of the bends will change and affect the shifting geometry. P stands for Muncie Plant.
Grit that gets into the grease in the shifter mechanism can cause real problems. This product is a very high-tech planetary overdrive. These are easy to adapt to a wide range of hot rods. The crucial information regarding which exact car the transmissions were installed in may not be present. It usually begins with 18S101350 or 28N12950. This means the Muncie was assembled December 13, 1967, for the 1968 model year.
Go slow and take your time. The smaller 6207-type bearing replaced the larger 6307 bearing in 1963. If you are rebuilding your transmission yourself, be sure to use a factory service manual. Muncie 4-speed Transmission Group 4. These have a 10 spline input and 27 spline output. He had been rebuilding four-speeds, as a hobby, since as early as 1990.
Some of the best Muncie builders participate on that page. This means the Muncie was assembled December 13, 1967 for the 1968 model year. Tailhousings often get damaged where the reverse shifter shaft lock pin sits, and at both the shifter and main mount bolt-boss locations. Performance is what the Gear Vendors is all about. West can take a '65 case and put in later model stuff.