Pool filter identification

Griz

I have a Harmsco stainless filter system that was installed about 30 years ago. Has 7 pvc posts that have two filters each. Best I can tell it's a HIF 14. My issue is finding parts on line, specifically the lid gasket.

mindyabiness

Look like this?

Griz

No. Has seven holes for filters, and the hole for the return is front center.

Welwood

https://www.uswatersystems.com/top-plate-for-hif-7-14-21.html