[jeffschevelle]

Bill is correct - He beat me to it while I was typing the spiel below!

The mesh shown in Steve's and Bill's pics (which I call "Diagonal Mesh") was used on the 212's from their inception (1965 I think) through at least 7/14/1969.

However, as Bill noted the 65-67 version (and early 68 model year) has larger “outlined” embossed letters (not the small block letters in Steve's pic), and they have no silk screen on them at all.

Sometime during 68 model year they went to that smaller embossing. And also during the 68 model year they added the BEST WAY TO PROTECT YOUR ENGINE" silk screen.

( Steve, just keep your A/C lid on your 67 and no one will know the difference! )

I have pics of an NOS 212 Diagonal Mesh filter just like Steve’s in box dated 7/14/69. So the Diagonal wire orientation, and the small embossed letters, lasted AT LEAST that long.

At some point after that, the same wire mesh material was rotated 45 degrees so that the wires ran horizontally and vertically (which I call "Square Mesh"). I understand that the Camaro judging manual says that happened in late August or September of 1969. The earliest NOS 212 filter box I have found with a Square Mesh filter had 1970 as the newest model year application on the box (but had no box print date on the flaps); so that box could have been printed any time during the 1970 model year. After that one the next “no doubts” NOS Square Mesh box I have seen was dated 1973.

The version in Jason's pics with "expanded metal" mesh (which I call "Diamond Mesh") is the one that many have said was ALSO used during the 1969 model year, based on “day one” photos from original owners, and magazine road test article photos of 69 Camaros and 69 Chevelles with Diamond Mesh filters.

I must admit to having had my doubts about whether those filters in those old pics were actually AC filters and had not been changed before the pics were taken to some off brand filter with a thinner element material for better air flow. But I believe it now, because the details on Jason's filter prove that that version was ALSO being manufactured by AC in 69 (perhaps 68 and early 70 model year as well), for three reasons –

1. It has the small block-letter embossing on it, which went away when they reoriented the wire to the horizontal/vertical Square Mesh (which per the judging manual was late August/September of 69, and per my NOS box date records could have been some time later in the 1970 model year).

2. It has no indentions around the outside edge of the top surface. At the same time the small block-letter embossing went away, the top was changed to add those 8 indentions seen on later filters. (Later on the top went to 12 indentions, then eventually back to 8.)

3. On the bottom surface it has 8 indentions around the outside edge AND 8 indentions around the inside edge. At the same time the top changed the bottom was also changed to only have the 8 indentions on the outside edge, and none on the inside edge. (Later on the bottom also went to 12 indentions around the outside, then eventually back to 8 around the outside.)

So the small letter embossing means Jason’s filter is after 1967, and the shape of the top and the bottom mean it is before some time during the 1970 model year when the top and bottom changed.

Notice that the tops and bottoms of Jason’s filter and Steve’s filter are IDENTICAL on all those details. That puts them within the same time frame of 68-70. Which means that during at least part of that time frame AC was using both the square-holed Diagonal Mesh AND the expanded metal Diamond Mesh. Maybe that was different AC manufacturing plants, or perhaps even different lines within the same plant(s).