Old Am Std Tub/Shower Valve

Help me identify an old Am Std Tub/Shower Valve

I need parts for an old Am. Std. t/s valve that nobody seems to be able to identify. I'm guessing it is 25 to 35 years old. It is a one piece unit (from top to bottom) it has 2 shower heads, a diverter, a temp and volume control lever, a handheld, another temp & volume control lever, and a tub spout. The handheld operates like handspray on a kitchen faucet, it has a trigger on the handspray. All are in a straight line from top to bottom, the whole unit is only about 6 to 8 inches wide and about 5 foot tall. It recesses in the wall, and has 2 acess panals. and the entire front of the unit is plastic. ( even the tub spout) Can anyone help me identify this valve!!

shower panel

Delta made a unit like that, but I have never seen one by American Standard.

Clearly marked "American Standard" however there is no data tag inside service panels

shower

My feeling is that it was made by someone else and rebranded as an American Standard. Without seeing the mechanism, it is difficult to tell if any A/S parts would work in it.