Early replacement oil pan gasket sets had two front rubber seals, one noticeably thicker than the other to accommodate the different pan/timing cover gaps. I don't remember what year the change in deign was made. I've encountered the problem frequently when working on an older engine.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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