Summit Racing catalog lists two types of oil pan gaskets for 350 ci: thick or thin front gasket. How can I determine which one to order by looking at mine? What about one piece oil pan gasket vs 4-piece?

pre 68 gets thin post 69 gets thick, 1 piece is a solid 1 piece of rubber and will NOT leak...

DEFINITLY GET A ONE PIECE... MORE THAN WORTH THE EXTRA $$

Whether thick or thin is determined by the oil pan you use. All aftermarket pans I have ever used required the thick. If you have to guess go with thick.