I have a big block 727 with a B&M aluminum 4 quart more than stock pan part #10280.

I can't get the pan from stop leaking. It only leaks from the front side of the trans pan aka closest to the bellhousing.

I've done just a rubber gasket no RTV sealer.

Two rubber gaskets with no RTV sealer.

Rubber gasket with a good amount of RTV sealer. And it still leaked.

I then used a rubber gasket with a medium amount of RTV sealer hand tightened the bolts and tightened after an hour. It is still leaking. I made sure the bolts are tight, tightened a little more and its still leaking.

The top of the pan where it meets the bottom of the trans is completely flat. The stock pans have the little ridges on the top of the pans.

Anyone have problems with aftermarket pans not sealing ?