I don't have a diagram, but it's obvious there should be a left and right high pressure line that goes to each side of the rack piston. I have the same problem with my 1992 745 (non-turbo). A year ago I noticed a leak, but didn't know where it was coming from. My first remedy was Lucas Power Steering Stop Leak. After going through 2 bottles of it, the leaking slowed down but not completely. That's when I removed the belly pan to try and pinpoint the source and discovered the steel line(s) had pinhole leak(s) around the middle of the rack. This is where salt and sand can collect, corroding the lines. It amazes me why stainless steel brake lines and high pressure power steering lines aren't required by law.

I tried to find out if replacement lines were available to no avail and figured one day, when the situation got bad enough, I'd have to try and fabricate new ones from brake line tubing, or at least replace the bad section(s) using standard Ford brake line flare fittings.

When the cold weather came, the PS pump got very noisy on startup in the morning because of the high viscosity of the Lucas sealant in the fluid, but the leaking had stopped. I expected the leakage to start again in the Spring, but so far I still haven't had to top up the reservoir and I'm not leaving fluid on the ground, so I'm going to leave well enough alone.

Anyway, I'd still like to know if replacement lines and fittings are available and where to get them and even how to identify what steering rack I have.