I was just looking at our lovely online NHRA rule book and from the way I am reading things a diaper is not required until you get into advance ET running 7.49 or faster am I reading this correct?
Under super pro running 7.50 or slower it states a diaper is permitted but doesn't say required.

70 duster full chassis super pro 416 CNC Indybrock heads 727 w/brake

best so far 1.212 60 6.219 in 1/8 at 110.88 9.768 at 137.81 1/4