Trans. right or wrong

I just got a 88 cherokee with shift problems, was told it just had trans changed. I believe this unit came with a aw4, 4 speed auto, but after putting on hoist i find they installed a 30-40le, by the id tag, could this be the shift problem.

Define and fully explain "shift problems".

The AW-4 and the 30-40le are almost exactly the same.

Drive seems go and solid but will not shift out of low automaticly or manully