I have a set of rear 1LE brakes that came off my 1989 Turbo Trans Am (11.7" disc brakes). They are in good working order and they came off the car at 58k original miles. Brake pads are practically new. Only reason I'm selling is because I swapped the rear to a Dana 44 and it already had G-body style disc brakes on the back. I don't know if you need to use a different caliper bracket for a non-1LE car, but if you need them the GM part numbers are 10136854 (Mounting bracket, RH) 10136853 (Mounting bracket , LH)

You can find a complete list of parts, instructions and part numbers here
http://www.ws6transam.org/1LEbrake.html#1LErear

Located in Lebanon, MO Local pickup is obviously free, but will ship for actual cost UPS ground service.
Asking 350$

Sorry stuff is a little dirty in pictures. Rotors got some surface rust from setting. They were recently removed, but the car sat for a couple years in the garage while I was building the motor, transmission etc.