Let’s clarify what’s a seal and what’s a gasket. The seals are in contact with the crankshaft the front is a one piece in a metal frame that is pressed into the front cover it actually rides on the damper boss. The rear main for this engine is a two piece that is within the main cap you can’t see it without removing the rear main bearing cap.
The gasket for the pan to block closes the pan along the length of the engine and side to side at the front timing cover and the rear main cap. All of it is visible with the pan removed. This can be a 4 piece gasket with 2 long sides for the length of the engine and 2 half moon pieces for over the bottom lip of tge timing cover and the rear main cap or it can be a one piece gasket that molds all of these elements of length and width together. The one piece can be found for the 1976-1985 engine with the two piece rear crank seal with another version that fits 1986 and up engines with the one piece rear crank seal. The one piece gasket is different for the older two piece rear seal to that used by the one piece rear seal engines, this also applies to oil pans not interchanging across this seat type divide. The 1955 through 1975 is also a two piece rear main crank seal but uses a thinner thickness gasket at the timing cover than the 76-85 pan gasket set. Often the 4 piece gasket set includes both the thinner 55-75 and the thicker 76-85 timing cover chin gasket.
Installation of the pan gasket set whether the 1 or 4 piece set requires removal of all the gaskets that close off the pan to block rails, over the rear main and from the chin of the timing cover.
Keep in mind that hardware store RTV does not resist oil or fuel for that matter. If using RTV it must be Permatex and it must say oil resistant or oil proof on the label.
An aside but something you have to watch for is the dip stick moves from the left side to the right of the block. You have to pay attention to this when buying pan gaskets.
Don't expect help from the parts store clerk unless it’s some old guy that’s been in the business forever. The young guys only know what the computer has to display, if you get off their data base your most likely on your own. Therefore, you need to do your homework which once again leads to buying books on the subject. As I said before, there is tons of great info out there that didn’t exist in the public domain when I was young. What you need is Ed Staffel’s “Chevrolet Small Block, Parts Interchange Manual” this lets you get armed with info before you go shopping.
Bogie
