The oil filter flange is between the oil cooler and the block. Do you want the oil cooler o-ring or the filter flange gasket?
This?http://www.autohausaz.com/search/product.aspx?sid=lafyt54532dax5451sxc5xnd&makeid=800026@VW&modelid=1285455@RABBIT%20L&year=1984&cid=20@Engine%20Parts,%20Seals%20%26%20Gaskets&gid=5432@Oil%20Filter%20Gasket