Trying to get ready to sell the 1989 Firebird formula after 20 years. Transmission has been having issues. I filled it with fluid but it's not shifting. What could it be? It's a tbi 305.

 

You're positive it's filled correctly? (With it running and warmed up, switched through all the gears and then checked fluid level?) did you mess with the detent cable at all? Is it properly set if you did? If all that checks out then she might of bit the dust

 

I haven't messed with any cables. I checked it warm and in park. I did not manually shift through all the gears. I can try that next. Thanks Dust where?