I am about to install or have installed new leather seat covers in my '89 coupe and when I removed the seat back to have a look I found the tubing going to the bladders was brittle and broken.
I found a few possible replacement tubing choices in the McMasterCarr catalog and ordered 3 possible replacements.
The order arrived today and one of the choices was a perfect replacement.
For anyone who may run into this problem, the tubing that matches what was in the seat is:
D.O.T. Nylon Opaque Tubing for Air ( choose a color) 1/4" OD .17" ID part # 5097T41 @ $.69 / foot 10 foot minimum
Now I have decide if I am brave enough or have enough time to do the replacement myself.