[WorkinProgress]

Thought I would post this to show the differences between the 1969 Camaro ducted hood air cleaner flange and the 1970-72 Chevelle cowl induction air cleaner flange.

The '69 Camaro flange has its thinnest point around the nine o'clock position when installed. The GM part number of that flange is 3955230 and can be found in Group 3.417 in the parts book. That part was superseded to 3975986 on 12/71.

There are two different Chevelle air cleaner flanges that use the same part number 3975986. The early style shares the same continuous lip to hold the seal in place as the Camaro flange. There is one difference with the Chevelle flange. Approximately the eight o'clock position it has a flat spot that the Camaro flange does not have. I have taken a picture showing the early NOS 3975986 on top of a Camaro flange so you can see the difference. Not sure when the full lip Chevelle flange was changed to the sliced off flange but it must have been short lived. The box the NOS full lipped flange came in is dated February, 1970.

The most common Chevelle flange has the sliced off side of flange.

I have taken pictures of all the flanges to help identify them. First picture is a 1969 Camaro flange that has the rear sticker on it. Second picture is the NOS early Chevelle flange. The rest of the pictures are self-explanatory.