I guess that you are talking about the cork pan gaskets that go on the ends. I found it necessary to soak the two end pieces so that I could draw down the pan. I would recommend using a little RTV in the corners.

1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed

My Chevy Master 4 Door is on the Road!