Looks to be a Borg Warner 1356, similar to the one I just worked on (mine is mated to a Ford E4OD transmission). They came in 4 common configurations, electric shift, and manual shift, flanged output or splined output shafts.
There's an ebay seller
transdeals4u (
18076) based in Redding CA that I used to purchase my parts from, that I would recommend.
This is a gasket and seal kit for a 1986-90 Ford Borg Warner 1356 Transfer Case. This is for an Aluminum Case, Cast "13-56".
https://www.ebay.com/itm/Ford-BW1356-BW-1356-Transmission-Transfer-Case-Gasket-Seal-Kit-/173519640602?_trksid=p2349526.m4383.l4275.c1#viTab s_0
I hope that helps