Transmission!!???!!! HELP!!!

The three and four speed transmissions do not share a common bolt pattern to the bellhousing. The two patterns are totally different. If it grinds trying to up or down shift, the first thing I would do is inspect to see that the clutch is disengaging all the way. If the clutch is worn out, it will not disengage properly and will cause grinding while trying to engage the transmission in a gear. Try adjusting the free travel. That's the amount the clutch pedal moves down before you can feel it engage the pressure plate. Simply depress the pedal with your hand slowly and you can feel when it begins to engage. There should be one inch of free travel. No more. If it has a good bit more, try adjusting the free travel correctly and see what happens then. Unless they've been abused, these transmissions....even the light duty ones are pretty rugged. I would try adjustment first. Just because it grinds, doesn't mean it's bad.