I have a 4wd 1st gen, and it used to have the RWAL system. Well, the ABS took a crap, so i removed the ABS dump valve, and proportioning valve, and just put on a conventional proportioning valve.
The only PITA was the fitting for the rear brake line that goes into the prop. valve is a different size between ABS prop. valve, and conventional prop. valve. Just had to cut the line, and use a different fitting, and reflare the line.