The transmission case has stripped bolt threads, bad leak, now its sticking and slipping. No doubt,it need to be replaced.
I know jack about transmissions, except that I cant afford a new/remanufactured one.

Will an 85' 700r4 out of a Corvette fit?

Which Chevy years and models have the same 700r4 as the one in an 84 camaro?

 

You need a 700R4 from a Camaro or Firebird - they are the only ones with the torque arm mount. Prefer 1988 - 1993, there were internal changes in mid-1987 trannys that make them better/stronger. Later years have electronic speedo, you have cable driven - just need to swap your tailshaft housing onto the newer tranny.