the 69 body assembly manual shows the pinch weld blackout extending to the pinch welds behind the rear wheels all the way to the tail panel.
Yes that seems to be typical at all three plants that year
the undercarriage of mine showed black overspray. i couldn't see anything behind the rear wheelwell (it was heavily rusted and the panels had been replaced in the back).
Well with rust and panel replacement you don't have allot to provide you guidance
......however, the picture of this 69 mustang in mustang monthly does not seem to indicate any blackout in this area.......did the factory ignore this area behind the rear wheel well? is this 52 mile mustang an exception? was it plant/day specific?
As we know sometimes workers cut corners and sometimes inspectors caught it and other times they didn't. In general, from the original cars I've seen I would say that the vast majority of the time this section was blacked out. Do have examples built just before your car (172xxxx area) and ofter (182xxx) with that area blacked out - for comparison
Have seen that late Dearborn car in person and it does have a number of different process's apparent in its build. Was very interesting but until we see other examples the same I'm reluctant to apply what we see on it to all other 69 Dearborn cars - but will continue to look and have an open mind
