I was going to make a post about this as well. I received my new air filter and was surprised how yellow the thing was compared to the one that came with the generator last year. I actually thought it might have been old stock. But the unit seems to be running well with it. Have not had any hunting.
The yellow pleated filter on the bottom is the one I'm searching for. I think (and Generac customer service has been of no help on this) the yellow filter is a 0J8478S. The "S" suffix is the key, and appears to be the latest upgrade.
However, I ordered a J8478S from Amazon and got a filter similar to the one on top. This is not going to help my engine hunting.
If anyone can help me with info as to where to find the yellow pleated filters I would sure appreciate!! I need one today.