Dennis- Sounds like the trailer connections were "remodeled" since new. So far as I know WRV has always used standard wiring (although the occasional coach does go out w/wiring switched as to proper pin-outs). You'll probably have to do the old method- hook up a buzzer sequentially to each wire, go to the wheel & put on turn signal(s), brakes,... till you've identified the wires, or trace the wiring back to good stuff & do a standard rewire job from there. The one thing I didn't get in the owner's packet was chassis wiring; have coach 12V & coach 120V, but no running gear wiring. Don't know if that is available from WRV for a 99 (or 06 for that matter).
Baja-tested '08 2-slide 36'
Alpine: The Ultimate DIY'er Project