[blue71ta]

Originally Posted by PB

Here's a thread where we've hashed out some of the stud vs. non stud air cleaners over in the 70-72 GTO forum.

http://forums.maxperformanceinc.com/...am+air+cleaner

it's my belief (and as evidenced by that previous thread), that the RA air cleaners with the 2 flat spots on the rear of the bowl area are the Service Replacements (over-the-counter, dealer units). The production ones I have don't have that, but the NOS SR one I had did. Also, the production one I have (455 HO) has the studs, but the SR one did not. Just my 2 cents...