Master Cylnder line location

I am working on a 95 Chevy Lumina NON-ABS. The guy replaced all of his brake lines from the Master Cylinder back and now the Right Rear Wheel locks up when you hit the brakes hard. He thinks he may have a line in the wrong location, which I believe is what happened. But I need to know which line, from the master cylinder, goes where?

From the m/c they go to a proportioning valve then to the rear, no?

Well there no proportioning valve around the master cylinder like most but I didn't look under the car, I can see all 4 lines go straigh down when they come out of the MC, and then the rear 2 go under the car. There is only 1 line that has an adapter on it at the master cylinder.

I would wonder if he has a lotta air in the opposite line, which will affect the diagonal front brake as well. With only one front and one rear supplying good braking, it's gonna lock and drag the working rear when the vehicle nose dives and gets light in the ass end...

Try proper split diagonal bleeding procedure if not done already.

I thought of that as well, but the pedal feels great.

All disc brake cars/trucks have proportioning valves, on the 95 they are built into the m/c I though it was seperate.