3 speed trans
 

what kind of 3 speed transmissions came in 60-66 chevrolet/gmc trucks? Muncies? saginaws? I need to know the gear ratios. I have an old trans that i pulled out of one of these truck. it has four bolts holding the side plate on. thanks

If it has a 4 bolt side cover it is a SM318. These are sometimes called Muncies, but they have nothing in common with the Muncie 4-speeds. Normal gear ratios are 2.94, 1.68 and 1:1. First gear is not synchro.

These gearboxes are similar to passenger car trannies from the same years and car trannies are sometimes swapped into the trucks. A quick way to tell the two apart is to look at the lower ears that bolt to the bellhousing. On the truck boxes those holes will be threaded and on the cars they won't.

Ray

trans
 

thanks for the reply. the two bottom bolt holes on the bell housing are not threaded but the top ones are. where can i get rebuild kits for this trans? someone told me that they are bad about jumping out of gear while you are driving down the road. what can be done to stop this? also. what gears do i count to make sure what the ratios are? thanks.

i don't know about counting gears but i think the gear jumping is very common in the SM318 tranys but instead of trying to fix this people just put a floor shifter in which doesn't really fix nothing, i would rather have it in the column. first try new rubber bushings in the column to get rid of the slack that should stop the jumping out of gear ,,,or anything that gives it slack you should replace. if this doesn't help then your synk is going out or you have a worn or broken gear.I seen on ebay once they had rebuild kits for the muncies i don't know if they were for the sm318 or not but you could search........ www.ebay.com or do a search on the net for sm318 hope i helped good luck keeping the truck original