What are these rubber pieces on my 2007 tahoe rear diff fill plug?

[dpx2]

I have a road hum when I drive my 2007 Tahoe (rear end is a G80) so I thought I'd check the read diff fluid. When I pulled the fill plug, I found about five 1/2" rubber pieces that are about as thick as pencil lead, stuck with some grease/sludge on the fill plug. They are definitely flexible. Any idea what these could be from? I know the truck had a pinion seal replaced at 78k miles, long before I bought it. It now has 173k on it. I didn't drop the cover yet, but plan to.
Any idea what these pieces might have come off of?

 

[dpx2]

These are the pieces

 

[Blackcar]

If they used RTV on diff cover what squeezed to the inside may of broke loose.

 

[Fless]

Moved this to the 2007 section for you.

 

[dpx2]

Moved this to the 2007 section for you.

Sorry, I just noticed the sections are based on model years. Appreciate it !

 

[dpx2]

If they used RTV on diff cover what squeezed to the inside may of broke loose.

Possible, but they are so uniform, not like something squeezed out of a tube?

 

[gooffeyguy]

Looks like part of an o-ring. From where, I can't say. Does the fill plug use an o-ring, I can't remember?

 

[dpx2]

I didn't see an o-ring on the fill plug, so maybe that's it. The pieces don't look like they were ever round tho, straight as an arrow.

 

[Geotrash]

My money is on RTV. When it gets laid down in an even bead with a caulking gun like a shop uses and squeezed out between parts, it’s often in a perfect toothpick-like shape.

 

[dpx2]

I guess when I pull the cover I'll know if there's a gasket or rtv was used. I'm hoping gasket so I can re-use it. Otherwise I'll have to clean it up really good and use RTV to put it back on, which I've never done. And, it'll be in a cold garage - which I read you should only use RTV in temps 65 degrees or higher. That might be April before I can use it..lol..it's going to be only 25 degrees for a high for awhile here in Nebraska...