1971-1972 GTO & Formula ram air cleaner ID
 

I have three ram air cleaners off of 1971 - 1972 A-body and 70 - 74 Formula cars. All three have minor variations in construction. I'm trying to determine what application each of these fits. I know one is 455HO because it has a hot air tube on the passenger side, but I'm not sure what year. I'm also not sure of what the other two are. I suspect one could be bought over the counter.

See the photos. Air cleaners from left (1) to right (3)

Differences:

Air Cleaner 1 D-port (left)
- 4 wire/vacuum hose clips on bottom
- One flat at back
- Flat straps on dashpots

Air Cleaner 2 455HO (middle)
- 2 wire/vacuum hose clips on bottom
- Two flats at rear
- Curved dash pot straps

Air Cleaner 3 D-port (right)
- 3 clips, appear to be dual (different from other air cleaners)
- One flat at rear
- Flat straps on dash pot

Here are some close up photos of air cleaner 1.

Air Cleaner 2 (middle).

Air cleaner 3 (right)

What do you want for the middle one?
I'll look for the thread of mine.

Here it is...
https://forums.maxperformanceinc.com...d.php?t=872998

1. 1974. 2. over the counter replacement of 1971-2 and 3. 1973.
No tag or even glue residue on the sides of base?

I need one 455HO air cleaner for my 1972 455HO convertible.

I'm trying to determine if the 455HO air cleaner is a 1971 or 1972. I thought there was a difference between 1971 and 1972, but I don't remember what it is.

I'm not sure what you're asking "No tag or even glue residue on the sides of base?" The no 1 air cleaner has a piece of tape covering the two holes at the back. I'm not sure why it's there. I think that one either hasn't been run, or has been cleaned up before I got it.

The difference was studs (1971) vs no studs (later in '72) on the diaphragm hold down.
If you have no tag or residue, it's been restored or an over-the-counter replacement. The scalloped hold down didn't show up until the '77 Pontiac air cleaner.

This is off of a late '72 Formula.

Interesting on the late '72 RA air cleaner. Usually the later ones had no studs.

I junked a 1972 Formula 455HO many years ago, the air cleaner was in the trunk and was covered in surface rust. I don't think it had the stud on it. If I remember correctly, it was a December 1971 built car.