The
1981 F-Series brochure shows on Page 9 that the Custom got a driver's door switch and on Page 8 the Ranger adds passenger's door switch. And Page 18, which shows the options, confirms that as both the Convenience Group and the Light Group add a switch to the passenger's door for a Custom.
So, Rembrant, you should have a LG/Y wire in both of your door jambs that, if grounded, will bring the dome light on. (Shown on Page 52 in the
1981 EVTM.) If you can fish them out and install switches your dome light should come on with either door opening.
Pete - That was a good buy on the window regulator.
Gary, AKA "Gary fellow":
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Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI