Well i have desided on doing the AC3 mod to it but i would like to find a service manual to know where to wire everything up

Why do the AC mod on it when you can get a dual-side player with AC3 already for a decent price? Is there something about it being industrial model that is important? Or is it brand new practically? Or just for the experience of doing it?

Well mainly because it is NOS for one thing which i only paid $15 bucks for and I just want to learn how to do it

You do understand looking at do-it-yourself AC-3 schematics using internet search is where you get the circuit and the names of the signals the circuit wants. Then you go to the Audio board schematic for the LD player to determine when you can get the signals the AC-3 circuit wants. You also need an isolated RCA plug to put on the back to provide the signal.