3spd to 4 spd conversion
 

hello all, I have a 71 chevy, with a 3sp on the floor, i have been think seriously about installing a 4spd, thinking a muncie m22, since this will mainly be a street vehicle, a very light hauling, I personal do not think it will take much to do so, but it would be nice to hear from someone who has done this before, I am still at the planning stage of my truck, so far the only thing i have really finished is the gauges, added autometer gauges to the stock positions, and thank you all in advance

Some three speed bell housings have a smaller hole that the trans fits into, transmision should be the same length so driveshaft shouldn't need to be modified, the yoke for trans will probally be different, different shifter.

so I should try to get the bellhousing and the yoke also, with then trans if i can find it used, say at a wrecking yard, or a trans shop

Check the length of the two trannys from the front of the case to the end of the tailshaft to determine the need for a new driveshaft. The swap itself is straight forward. Some early bell housings were application specific, but most will accept either the 3-speed or 4-speed. Since you will need a new front yoke, if you need a new driveshaft anyway, consider a 1-piece--1 less u-joint to maintain and eliminate that pesky carrier bearing. You will have to cut the bottom of the crossmember out for clearance. I had one made out of much heavier stock by TruckPro for under $200. Also, the shifter location may be different due to the different lengths of the trannys. Good luck and keep on truckin'.......Jerry

is your current trans a 4 speed with granny gear because i was not aware of a three speed on the floor comeing stock.

I asked that question in a diffrent forum, about it being stock, 3 on the floor, Im thinking it isnt, some has started re do this truck, before i got it, the steering column is clean, no hint of a shifter,


are the crossmembers diffrent for a 3 sp and a 4 spd? and I do agree going with a one piece shaft would be a better way to go, I appreciate all the input,

you might want to look into a different transmission the m22 is awesome but they are very expensive to get a hold of

any suggestions, on what might be just as good, and readily availible,

Check into the m-21 and m-20. I really like both of them.