Around the middle of the second season, keen eyed viewers could notice an odd little tab stuck underneath both of KITT's doors:
This tab would appear on K.I.T.T. throughout the rest of the season. Do you know why?
This was a welded on mount, added to the car for one specific reason - as a way for the crew to mount K.I.T.T.'s sidepipes for the second season episode "Custom K.I.T.T.":
In fact, to this very day, these tabs can be seen on one of the remaining screen used K.I.T.T. cars. Here's a close-up of it: