The part number was located on the air breather container, near the snorkel. It was a decal and the part number is 6423271.

I just received my original air cleaner and I'm having a hard time finding the correct air filter for it. The decal shows a AC Delco A427C. It's a little too tall, so the chrome lid won't close all the way. I believe the A 212CW was the replacement air filter. I have tried Fram and Wix, but had the same problem. I tried a K&N E-1650 and it was better, but still didn't close all the way. Most are 3 inches in height, but I think the width of the filter itself is the key. If its slimmer, the rise in the chrome lid allows it to close more.

If your are using this air filter, what brand and part number are you using? Thanks!