I have both left and right rear e-brake cables and the front center one but i dont have the part that connets all three together. does anyone know whats its called or where to get one?

Are You Referring To P.N. 6 In The Drawing,If So It's Called An Equalizer.

is there a schematic for the 91'-92' cars like this available somewhere???

Junkyard

Beware there are two different types, ones like the diagram have a threaded portion of the cable going to the handle and can be adjusted as needed. Others like drum brake cars Ive seen use a fixed crimp on the cable so no adjustment can be made

Seems like it would be a good idea to upgrade to the adjustable setup if he has everything apart. Grab the equalizer and the cable from the donor. Can this be done?

got the equalizer from pull n pay installed it an works perfect got 2 (different) e-brake cables just to be sure

So if i get the "Y"-point tentioner, would I need to swap out the other two cables to the rear brakes as well to have this installed on a 91'?...and can it be installed on a 91' since General Monkey changed it it to a straight cable only?

yes and no. it depends. let me explain.
i have a 91 that was converted from drum to disc. (9 bolt disc from an 87) i used the disc brake cables, not the drum cables. i have to switch the equalizer out from a non adjustable(91)to an adjustable (87). HOWEVER...the mounting point to the brake handle for the disc equalizer(87) is different than the drum equalizer (91). the disc equalizer will not mount to the 91 brake handle. therefore i have to switch to the 87brake handle. the attachment on the disc is held in by a pin and the drum equalizer is not.

So I would have to switch the rears from drums to disc and get a older style (1987) brake handle and everything else to make it all work?

to make it all work correctly, yes.

Here's The 91-92 Diagram If It Will Help Any.