I am trying to fix a leak between the tank and bowl on a circa 1935 crane siwelco toilet made by trenton potteries.

Standard tank gaskets don't seem to fit the opening in the base (bowl) - it is an oval about 31/4" by 41/4". I tried making a gasket myself but was still getting water leaking. Also tried a wax ring but no luck.

The tank secures to the base with 4 bolts that are all outside the tank.

Any suggestions would be appreciated. Thanks.