just curious and checking to see what files people usually mod and/or mod the most. this could be files you have downloaded to use or your own modified files. i keep mine fairly basic so there is less to replace if i ever have to verify my game. i do know there are some out there though that really get into modifying their files to the point it is almost a different game (figuratively speaking).
the basics of mine,
film grain removed
winch line changed
winch points changed
fuel cistern and tanker recolored
fire proof exhaust recolored
key/controller overlays removed (although yet to figure out how to get rid of the overlay box for it)
mudrunner mod (STplus as most call it)
steam icons removed
and i know there is a few others, but can not remember what or they are little things that are not that important.