Transmission problems

Hard shifting into gear can be caused by a clutch that is not releasing far enough, either due to mis-adjustment or a hydraulic problem, depending on which type you have. When you add the additional symptom of popping out of gear, both problems are more likely to be caused by a worn synchro. That is a brass ring that slides over teeth on the side of the gear to mechanically lock that gear to the shaft it is spinning on. As you move the shift lever, the first thing that brass ring does is rub on the side of the gear to cause its rotational speed to match the shaft's speed, then, as you push further on the shift lever, it is easy for that ring to slide over the teeth since everything is turning at the same speed. When that ring becomes worn, it does not rub on the side of the gear hard enough, then the gear can be spinning too fast or too slowly. It is like trying to hop onto a horse on the merry-go-round while it is running at full speed. You might do it if you run fast enough, but expect some grinding to occur!

That is beyond the scope of my memory banks. Your best approach is to ask at any salvage yard. They will have large and very expensive "Hollander Guides". Those are books that list every part for a specific model and year with a code number. You look that number up in the back of the book, and it will list every model and year that part was used on.

If you are willing to do some research, you can also look on the internet for transmission suppliers and rebuilders that list their inventory and part numbers. To do this, you need to already have a donor car model in mind. If you are lucky, they will list all the models at once that transmission fits. I use the Rock Auto web site for reference almost every day. If you look up the transmission for two vehicles and the same supplier lists the same part number for both, you'll know they interchange. The problem is when the part numbers are different, you don't know why. That difference could be insignificant, as in one has a threaded bracket mounting hole that you do not need, or they have different gear ratios.

Be careful if you go by pictures only. Two transmissions can look the same but be not interchangeable. The input shaft diameter, number of clutch plate splines, length of the housing, and mounting points could all be different.