I am doing my BB '70 402 frame off and have a non original Muncie 4 speed that I want to use. I think the side plate #'s state it's a '67-'68. Will there be any issues? What size driveshaft should I be looking for?
Thanks,
Roland

The 1970 M20 and M21 should be the same as the earlier M20 and M21. The M22 changed in 1970 and the other Muncies changed in 1971. The driveshaft can be a 1968 - 1970 driveshaft. The 1971-1972 driveshaft is shorter as is the 1970 M22 driveshaft.

I am doing my BB '70 402 frame off and have a non original Muncie 4 speed that I want to use. I think the side plate #'s state it's a '67-'68. Will there be any issues? What size driveshaft should I be looking for?
Thanks,
Roland

Transmission will bolt in no sweat. Possibly the method of retaining the arms to the shifter forks will be different. In 67 thre were studs that came outta the side cover. You used a NUT to attach the Hurst levers to the trans. Somewhere along the line they went to an arrangement wherein you used a BOLT to hod the levers to the trans. I cannot recall when that was. Might have been after 68 certainly at some point in the 70 / 71 / 72 timeframe. This is not a show stopper but you might need to replace the levers taht attach to the trans shifter forks.

Drive shaft might be an issue, actually not the shaft so much as the Yoke. The older transmission used a more or less universal yoke that fit nearly every trans GM offered. Later the yoke sixe (diameter of the section going into the into the trans) was bigger on some stick yokes and some automatic yokes. If your car was a stick before LENGTH of the shaft is not an issue.

Universal cup diameter might also be different on the yoke that fits the 67 trans and the driveshaft from you car. This is nto a show stopper eather. Good parts stores can get ya a special universal that has different size cups on each axle allowing for the differences in sizes of the holes in the d-shaft and the yoke. This 'universal" universal can be used in eather the front ot the rear or in both locations if you have issues matching the Yoke cup dia to the dshaft cup dia in the rear matching the dshaft cup dia to the pinion flange diameter / cup size.

OK guys,
This is what I have from what you answered back to me. It is definately a bolt on shifter and linkage. I think, as it was told to me, a wide ratio. I will be looking for a driveshaft, so that's why I am asking. I think the input shaft is 13 spline and the output shaft is 31 spline.
Thanks
Roland

I don't want to hijack the thread, but I've got a question. My dad said I could borrow the drive shaft out of the '70 (55.5") to put in the '71. From what I've been told the TH400's need a 54.5" drive shaft. I want to see if the TH400 that is in there is a working unit, or not. Would that extra inch cause major problems? I am not sure if that extra inch will make it to too long and cause it to not let the rear U-joint seat in the pinnion.

If it's an earlier Muncie the input would be ten splines, and the output would be 27. Later ones were 26 on the input and 32 on the output.