G238 Transmission woes

So I have a 2006 Dakota 4x4 and on the way home from a Xmas party
Saturday night, my designated driver says 'hmm, it won't stay in 6th
gear'  And she was right, first either.  I thought it was the clutch
but have now found out that it's def the transmission.  We've taken it
out and apart and it got so hot that parts of it have welded together.
To make matters worse this transmission is completely un-findable in
all 50 states, even Chrysler doesn't stock em.  Has this dilemma come
up here before?  Anyone have any helpful insight?

-gj