The original military manuals, linked at the top of the forum pages, dont list a sealant...it seems to make sense but it isnt spec...you could try...
The rear main is a leak prone place...unfortunately.
As far as getting it out, yes, did that myself. Installing the new one, I had an old time engine guy who owned an engine shop since back then tell me that they put a piece of string up through the hole where the upper seal goes, then work it around so it hangs out both sides...so it goes up over the top like the upper seal should...then put a slip knot on the upper seal with the string and pull it through the groove...worked for me.
He, and others here on the site, indicated that not lining up the parting lines of the seal to the parting line of the block that holds the lower seal in place is a must to help stave off leaking.
Hope that helps...if you use sealant and it works, please post and let us know what you used and such...THANKS!!
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