I've been collecting pictures of 70 mach 1's from original ads, the Lawman Performance Tour of then new 70 mach 1's as well as other pictures of then new 1970 mach 1's and I've noted some very poor factory fitment issues in regards to the argent aluminum rocker panel mouldings.
The passenger sides seem to be okay, but the drivers side fitment seems to be the most common areas where the fit was not that great and these cars really showing they were built like any other assembly line consumer item.
Specifically, I've seen on several 70 mach 1's - the drivers side where the top brightwork doesn't line up, where sometimes the fender or smaller quarter rocker piece was actually canted a bit but noticeable - and where the height was off as well - the door rocker panel portion jutting out a bit from the lower door rocker panel.
As years go by, owners and experts often assume its because of accidents, sagging door hinges, time etc - which sometimes IS the case for some cars.
But after many years of restoring etc, this factory fitment issue tends to get forgotten and owners and restorers shaking their heads.
Case in point - check out the Kelsey Hatyes ad I posted in Misc section of a black 70 mach 1.
Wish it were a larger pic as posted (the original ad shows quite distinctly) - you could see how far out the door rocker steps out and leaves a noticeable irregular look. The rear quarter piece is not aligned well and one can see at the front of the door rocker panel how the brightwork doesn't line up and sticks out from the fender rocker panel.
Its not just this car. I've seen it on numerous 70 mach 1's from original pictures.
As years go by restorers often correct this as best they can, but for some owners who can't figure out what's going on and know your car wasn't wrecked or the door hinges bad - it may just be that your car came from the factory built in such a way that when these rocker panels were bolted on, they had less than stellar fit and finish.
LH jigs off at the factory(s) a bit?
Steve