1800 oil tank

:facepalm:IM SO TIRED OF THROWING MONEY AT THIS BOAT. im needing a oil tank for my 98 challenger 1800 with duel 787. someone please help, these tanks are obsolete, I can not find one anywhere. it does not have to be OEM. im to the point IF IT FITS IN THE HOLE IM GOING TO STICK IT IN. Any ideas...