['ol Pinion head]

a few notes...
Rex's aircleaner is not a '70 base 4 bbl Pontiac air cleaner, the snorkels on those are quite a bit shorter & the base itself is different. Have a few in the racks & have pulled many dozen '70-72 455 big car engines over the years. Usually tossed most of their aircleaners, very little value.

The '79 301 aircleaners have the inlet snout exactly like the one pictured above on Rex's aircleaner. The end of the snout has the small slots stamped in it. Both the F body versions & the A-B-G series 301W version use a small diameter fabric type duct (just like in Chris's pics). The rear of the domed area, directly behind the Q-jet, also has the flat area, my '80 301 F body bases don't have that.

For 1980 models, the Pontiac 301 Firebird engines used 3 different aircleaners. The 301 turbo & the 170 horse 301 used versions of a new wide mouth snorkel aircleaner. I have always bought the '80 301 turbo version with the heavily angled down snorkel. Up into the mid 90's, these were relatively hard to come up with & they are different than the '81 version. The base 150 horse 301W '80 Bird aircleaner used a small snout version, but I believe it used a AC329 filter. Such a filter would fit in a 15 3/16" diameter base. Rex, when you lay a tape measure across the beaded edge of the top of the base, does it measure 16.5" or 15 3/16"? That's prob easier than looking for a 14" & 12.5" diam aircleaner filter to drop in...