Transmission wont go into reverse

[tjg]

Ok i have a problem with my 96 talon tsi awd manual i just got a remanufactered transmission from mitsubishi graveyard and i put it in like a week ago. Everything did work fine but now i have some trouble with the reverse it doesnt have it it doesnt even fell like theres a slot for it. I was driving earlyer yesterday and i backed out of my driveway and it was fine parked it and it didnt have reverse anymore, plus my fifth gear only stays in if i'm on the gas if i let go of the gas it pops out. Please give me some info on how to fix this beast, i really like driving it but it just wants to keep crapping on me.