Back when the "big push" was on to convert to metric, there was one year that Wix had ZERO application info for some GM cars, this was because of the great engine musical chairs, where you might buy a Buiacobile it might have a Ponch, Olds, Chev, or Buick engine. The Wix catalog just said "go out and look at the X figure of the VIN and if its' A use XXXXXX if ............and so on. and also that at some point, some of them changed to metric
Some had changed to metric, but mechs would outsmart themselves. They "knew" that a Wix whatever was the correct filter (former imperial thread) but now the car was metric. And SOME of those changeover threads were close enough that people would thread them on a turn or two and then FORCE THEM until something was damaged.
Yet another Great Screwup was IHC briefly used AMC engines in some of it's rigs. If you had an AMC 401, IHC renamed it to 400 to differentiate from the IHC built 401. BUT MECHS would outsmart themselves. They'd open the hood, and "oh, I KNOW, THAT is an AMC 401," and they'd come in and order parts for a 401. We'd look up parts for just what he said---and IHC with a 401---and he'd take the WRONG PARTS to the shop
