The bearing retainer plate...
The bearing retainer plate is Mopar-spec and is 1/4-inch larger than a passenger car and early Chevy truck bearing retainer-and bellhousing pilot hole. We took it to the machine shop and had it turned down to Chevy spec to fit in our original truck's bellhousing.
Because the MY-6 tailshaft is based off of GM dimensions, and the main case is the wider Mopar style, the only shifter that works is one of two factory GM units, both made by Hurst. They look very much like a Competition Plus shifter, and have a grease fitting, but they're unique to this transmission. Due to the narrower tailshaft, the shifter mount is closer to the centerline of the transmission, while the shift-fork levers are farther from the centerline. The fingers that come out the bottom of the shifter mechanisms have exaggerated bends in them, and the linkage rods also have big bends. Our two shifters have different offsets for the fingers, and the brackets that mount them to the tailshaft are correspondingly different. We also noticed that one of them is a decidedly beefier assembly than the other-bracket, shifter housing, rods, and all-leading us to think it was either superseded during the production run, or one was on a heavier truck. If you wanted to use any other shifter, you'd need to fabricate a mounting plate to move the shift mechanism out away from the transmission. We also checked them against the shifters out of Dodge junkyard trucks with the A-833 OD-they don't interchange, and generally appear like a lighter application than the Chevy units. We have both Hurst and Inland shifters from the Mopars.
One of the better-kept secrets in the automotive hobby is that Hurst has a shifter rebuild service. Our shifters had very sloppy gates-it was like stirring a pot of stew to get a gear. We sent one out over a year ago, the rebuild cost was $100, and it came back looking and working like an absolutely brand-new unit. We plan on using our own shifter handle, so we didn't use Hurst's handle rechroming service, but it's available. We've taken advantage of this service a couple times with other projects, and are always amazed when they come back. Since then the prices have gone up a bit, but it's still a screaming deal. The Chevy and Mopar shifters use any bayonet-style shift handle, and we've seen several different handles on Mopars; black-painted rod, chrome flat bar, chrome round rod ... any bayonet-style handle will fit. We found a black-painted handle from a Dodge van clears our bench seat nicely, and goes well with the spartan look of our interior.
Once the bearing retainer...
Once the bearing retainer plate was turned down, we found the original hex bolts hit the I.D. of the bellhousing's pilot hole, and wouldn't clear.
One failing of this transmission, besides the weaker aluminum case, is that it will weep fluid out between the countershaft and the register in the case. We're not sure how GM handled this when they were new, but on a Mopar, the bellhousing mounting surface fully covers the front of the transmission so you can spackle a thin layer of RTV where the countershaft comes through the case and then sandwich it between the case and the bellhousing. On our GM truck bellhousing, this area is open-no spackle, so it leaks. We solved the problem by fabricating our own steel shim gasket to go between the case and the bellhousing.
Finally, the bearing retainer plate also needs to be given some attention. They retained the Mopar-spec bearing retainer cover, which is about 1/4-inch larger in diameter than most other GM transmissions, specifically the passenger car and early truck transmission. The register hole in the later truck bellhousings compensates for this, but you'll need to turn down its outer diameter to fit other GM bellhousings, such as our original '62. Once the diameter is turned down, socket-head Allen bolts and lock washers replace the hex-head bolts, as hex heads will hit the sides of the hole. We used lock washers, and after touching the edge of the washers with a grinder, it fits perfectly. Note that the bolts holding the bearing retainer are not blind-they go right into the case, and need thread sealant, otherwise they leak.
 The easy fix for the hex bolts...  The easy fix for the hex bolts hitting the pilot hole is Allen bolts. These bolt holes go all the way through the case, and need to be sealed with something that will stand up to trans or gear oil. If you don't, it will leak like a sieve. |  On the side cover, only one...  On the side cover, only one of the bolts goes all the way through into the case, the others are all blind holes. This hole is on the bottom-side of the cover, is submerged, and will leak without sealant. |  To solve our leak at the countershaft's...  To solve our leak at the countershaft's bore in the case, we made our own metal shim gasket to put between the trans and the bellhousing. It was the thinnest material at Home Depot-it won't affect input shaft depth. The Chevy truck bellhousing is open at the countershaft bore, so we felt that the shim would deflect with a layer of RTV between it and the trans, so we bent a flange along the bottom and added a short bead roll to stiffin it up. These two additions made the lower portion of our shim rock solid. |