Help ID-ing and sourcing a part

[Disco]

Hey all. I just noticed the rubber of my driveshaft center support bearing is shot. Before it gets any worse, I should probably fix that.
The truck is a 78 short bed with a 350, a Muncie SM465, and a 12-bolt.
While doing some YouTube research on how that’s done, I’m seeing there is some sort of a lock collar on the second shaft on the splines that prevents the driveshaft assembly from separating while still allowing for slip. This collar needs to come off to get the support bearing off, and all the videos I have seen show there is a nylon or teflon seal inside the collar, and they always seem to disintegrate upon contact with fresh air.

I do not know what this seal is called, whether my truck will require it (all the videos are of later 80s trucks), or where to find it. I have already looked at LMC and CJ Pony, and I didn’t see it, but I might have looked right at it not realizing. Any help with this would be appreciated.

Also, if anyone knows a better way to replace that bearing that by removing the entire driveshaft, I’m all ears.

Thanks, y’all.

 

[squaredeal91]

I was half asleep lol, Edit. Got pics?
I think @legopnuematic nailed it

 

[legopnuematic]

From the 1978 service manual-

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No idea if this is correct for your application, but might give you some terms to search by.

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