Hmmm!… I’m a bit confused by the question (what’s new!!)…. I think we are speaking of which was the first pre- production (EX) Stude Avanti fitted at Paxton with an R3 (probably 299CI) engine?… I believe 63R1025 had the air cleaner assy up in front of the radiator, however, of course, that Avanti wasn’t a EX car.
Anyway, my guess is there was no air filter, other than possibly a screen to keep the rocks out?