I am rebuilding my SM420 4-spd transmission and I picked up a rebuild kit from Novak and have a question about which gasket to use on the input shaft cover. The Novak kit gave me two gaskets for this purpose a thick one and a thin one. The directions do not say which one to use. As luck would have it, I can find all the gaskets I removed but this one, so I can not compare to what was there originally. Any help with this would be greatly appreciated. Thanks.

Jim


1954 GMC 1/2-ton Longbed
1971 Pontiac LeMans Sport