Correct 1966 rear differential cover gasket
 

I am looking for the correct rear differential cover gasket for a 3.42 safe-t-track rear end out of a 1966 Pontiac Grand Prix. The standard gasket I bought - although of the correct configuration - is only about 10 inches tall and needs to be 11 inches tall.

Since all 1966 Big Pontiacs used the same rear differential cover gasket, I do not know why I am having this problem. My fallback is to use a Permatex product instead.

The correct gasket you need is Fel-Pro RDS 30031. For some reason it is incorrectly listed in almost ALL on-line catalogs for our old cars. May be a little tough to find, I don't know.

FYI, Rock Auto has them in stock. Felpro is discontinuing them. They have at least 10 on the shelf. $2.77 each. Get them while you can.

I ordered 3 gaskets for my 67 Bonneville @ $25 each with all being wrong.
I got some gasket paper and cut my own.

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I use "gray" silicone sealer and it's been there for 10+ years.

Thanks for the info, surprised so many sellers have the wrong info. My order has now been placed with Rock Auto.