What is this sleeve, and why has it pushed my seal out?

 

That's not a sleeve that is a bushing, that sits in front of the rear seal, it has spun and worked it's self back. The slip yoke is probably marked also.

 

Thanks for the reply. Can I drive it back in, replace the seal, and keep going, at least temporarily? Or is this a trans killer?

BTW, this is a 2nd gen Ram. I noticed I posted it in the wrong forum.

 

It's not a Trans. killer, usually what you would do is find a shop that can replace it, and tow the truck there. There is a tool that allows you to drive in a new bushing and seal, providing that the extension housing will still hold the bushing, if it spun too much it may not. the other question is why did that happen in the first place, are your U-joints OK?

I would not drive it very far without a proper repair, that thing will throw oil like crazy, to move it from one place to another. at an idle would be OK, I'm talking like 50 feet.