I had the same problem in my 1974 Camaro, long time ago. I ran over a large
tree branch or something, and the trans got stuck in first gear. The cable was
locked up, if you yank the console, it should be a relatively easy fix, and not
that expensive. If I were you, I would crawl under the car, remove the shifter
cable from the transmission lever on the side of the trans, and see if the
lever moves freely. If it does, then you should be home free with a new cable.
I've very rarely seen the stock auto shifters in those cars go bad. Good luck