Mats tech inspection

Been on the mats website to try to get some detailed info about tech inspection for different classes. They mentioned no leaking fluids and check your brakes and tires and also referenced checking dates on the seat belts. One question I have is does the date codes for the seat belts matter if you're in a 14 or 15 second car? What about if you are in the street class with original 45 year old seat belts? I have several different cars i could take. My big block duster has no inner fenders, does that disqualify that car?
So those are my first two questions, about when seat belt date codes become relevant (what e.t.), and no inner fenders.