I owned an 85; tranny went out on it as well.
yeah, it got locked permanently in reverse backing out of a parking space at the local Sonic Drive-In ... think it was fixable ... dropped $2400 on a new one ... would like to have converted to the 6-speed but couldn't mess with it at the time ... shoulda found a way though ...
I still have the orig tranny but it runs about $1300 to get it rebuilt ... I don't need a spare that bad ... but the car has never been wrecked so the fiberglass is excellent ...