No reverse or overdrive?
 

So I just dropped my trans and replaced my clutch on my 91 2.9 5spd. Wouldn’t shift at first so I went and bled the slave. Gears 1-4 work fine and drive but truck won’t stay in reverse. As soon as I start moving it kicks itself out, then when you try to make it stay while moving it grinds hard. And it won’t even go into overdrive. Anyone have any advice? Thanks

Wouldn't be an issue from changing the clutch

If its a 2WD 2.9l then you have a Mitsubishi FM132 5-speed
If 4x4 2.9l then Mitsubishi FM146

Neither were great transmissions

A 1990-1997 Ranger 4.0l M5OD-R1 manual transmission will bolt to the 2.9l engine, and would be better choice than trying to fix either Mitsubishi transmission
2WD or 4x4 would also have to match

Some 1988-1992 2.9l 2WD Rangers did have the M5OD-R1(M5R1) trans, if the transmission has no Pan(bolts) on the bottom its an M5R1