SVO oil cooler gasket

I'm looking to replace the gasket on the water-type oil cooler from an '86 SVO. (between block and oil cooler) it is a little larger than the gasket of the filter that attaches to it. that would make my job too easy. anyone know where to get a replacement for this gasket? maybe an oil filter from XXXX car that has the same size neoprene gasket?

Went to the dealer, after 30 mins of the guy telling me there was no oil cooler in his computer, he finaly found it and told me there was no listing for a gasket on it, and it was out of production and could not even be special ordered anyways. Then i went to the local parts store, no listing there either. i dont know where else to look, it doesnt seem like this would be an aftermarket piece.

-Ryan