That was why Marlin didn't try to produce an adapter for a long time, but then through testing, he discovered that the 3.0 t-case is in fact strong enough to handle the stress.  The taco case is probably stronger, but IIRC, marlin discovered that the 3.0 chain drive t-case is of similar strength as the gear driven t-case.

It probably wouldn't be too hard to adapt that crossmember either.  I made a chain drive t-case mount by cutting of one side of the mounting tab,and welding it on at a different angle. ...