Hi everyone, great forum, lots of valuable information. This is my first post and I would like to tap into the wealth of information found here. The truck I'm asking about is a 1970 R model, 237 engine, with a twin stick 6 speed. This particular 6 speed (I don't know the transmission model number) has a total of 6 forward gears, and 2 reverse gears. I've got one of our farm trucks under the knife for transmission repair due to no operation in 4th/5th gear, I had normal operation in reverse, 1st, 2nd and 3rd. I pulled the transmission and found the rear 4th/5th shifting fork broke. I turned input shaft and visually inspected what I could see from the two access covers on top of transmission, and I thought everything looked good. Hauled tranny to Mack dealership in Fargo, ND, where they told me there was also a shaft that was damaged and that parts were not available. They put transmission together without fixing it and we hauled it to Catco and they are having difficulties hunting down parts as well. I've got a hard time to believe that parts for this transmision are that hard to find. What source have you guys been using for older transmission parts? We have also discussed swaping tranny out to a straight 5 speed, but that may be difficult as well, as my truck uses a push style clutch. If I had a pull type clutch, then finding a 5 speed for it would be the easiest. Does anyone have any experience switching clutch styles? This mack, which we refer to on the farm as the "Old Mack" was our first diesel truck and I would hate to part it out, she's been a great truck for us over the years. Thanks everyone...
