Yeah, that's the obsolete style System-1. I don't believe there is any disposable filter that would give the correct oil routing with that, so you're stuck with using System-1 elements. Perhaps you'll prove me wrong- for your sake.
Caution: when shopping for System-1 elements, be advised that they used almost identical part numbers for the new style elements. So don't buy based on just the part number- you need to match dimensions. I learned this by buying one from Summit and having to send it back.
Also- you may already be aware- that elements were available in a variety of screen sizes. At least in 75 and 45 micron, and I think some finer sizes.
As for when these "got so old"... I'm not sure. I think it was about a year ago.