Whats it called

[Wilcox]

The gasket between the transfer case and the manual transmission???? Anyone know.

 

[RonD]

I doubt there is one at either end of the tail shaft housing, certainly isn't in need of a gasket at either end

The rear of transmission has a seal to prevent fluid from leaking out
And front of transfer case also has a seal to prevent fluid from leaking out
The tail shaft housing should have no fluid in it, and it has a weep hole in case either seal should leak

So just put some RTV around the edge for dust/water intrusion and bolt it together

Just FYI, rear differential covers never had gaskets either, Ford just used RTV to seal the cover, although you can buy 3rd party gaskets now
Maybe a 3rd party also makes them for tail shaft housing

It would just be called "transmission model" tail shaft gasket

 

[tw205]

I use RTV but rock auto carries them as transfer case gasket.

 

[Wilcox]

On my 1988 4 speed with overdrive the back of transmission does not have a seal. It has an open bearing that gear oil flows threw and allows oil to get to shifter. Yes I found the transfer case gasket thanks for the name of it. Yes the transfer dose have a sealed bearing stopping trany fluid mixing with the gear oil in transmission. Thanks again guys.

 

[Shran]

On my 1988 4 speed with overdrive the back of transmission does not have a seal. It has an open bearing that gear oil flows threw and allows oil to get to shifter. Yes I found the transfer case gasket thanks for the name of it. Yes the transfer dose have a sealed bearing stopping trany fluid mixing with the gear oil in transmission. Thanks again guys.

That's interesting, basically everything before 1988 had that style of transmission but 1988 and newer manuals had sealed tailhousings (M5OD and FM-146 transmissions.) Wonder if your trans came out of an earlier truck. Either way, the gasket is fine, RTV is fine too, whatever keeps oil in. On newer trucks it's only there to serve as an interface between metal surfaces. There is actually a drain channel cut into the bottom of M5OD tailhousings!

 

[Bronco ii Man]

Used RTV on mine and no leaks! Use it like the directions say and it will always work! Right RTV for the right application always good results!