Those part#s are non-Rohs compliant. So good chance Mouser wouldn't carry them anymore once their stock is out. Check for it's equivalent Rohs compliant part number.
Or use the Bourns 91 series conductive plastic. These are the ones I use on my preamp kits.
You can also check Digikey, but if you insist on a non-Rohs part, they're getting harder and harder to find.