True, that's what he said. But what he said is not quite true.
I know you know this, David, but for the others we've proven with anecdotal information that the date of 3/1981 is not entirely accurate. It appears that the changeover was done on a by-plant basis, and two plants kept using the slide locks past that date. For instance Twin Cities was still using slide locks as late as 07/81. And KC seems to have continued to use them for a while as well.
I have great respect for Bill/Numberdummy as he's forgotten more than I'll ever know about Ford. But we have evidence from many trucks that the slide locks were used past the 3/81 date. So I just wanted to make sure that people won't find your post and think that answers the question of when the slide locks were discontinued.
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