Job security:

#1 Ford diesel mechanic

#2 Ford Technician

#3 Blunder Motors intake/head gasket specialist, rear differential overhaul specialist, 700r4,......nevermind: too many issues to mention here

and,

#4 Dodge overdrive transmission specialist based on every 904 and 727 POS variant ever derived.

I'm sure toyota, Hyundai, Kia, and Mitsubishi body/mechanical Tech fits in there somewhere, but you get my gyst.