Jgibs, that RABS caused me so many damn problems on my 88.... I mean it worked when I first got the truck but holy cow it seemed to make things worse, especially in the snow, I prefer to control my own brakes thank you very much.
One of the first mods I did was disconnect the RABS computer, no more light, no more RABS. That RABS valve sat on the frame rail until last year, I finally finished my rear disc conversion and I got rid of it.
Here's what I had to do on my 88 with a 97 Explorer AWD rear:
95 Explorer master cylinder, no frills.
94 Explorer booster (junk yard, BII one had 240K on it
The drum brake lines on my 88 were a standard bubble flare, the new master is a metric bubble flare, which means that for the front brake line I was able to use a single adapter, for the rear I would have had to stack about 6 adapters to make the jump.
So I ended up running a complete new hard line back to the RABS valve. At the Rabs valve it was a simple adapter to bypass it, input line directly to output line.
RABS valve now sits in a box, along with the wiring and computer.
with the rear discs, D35 discs up front the little BII stops like crazy, even with the boat in tow its great! I played with the front/rear biast about 5 times before I got it just right, if I mash it the rears will lock just before the front...in a BII thats a good thing