They don't share the same fluid. The seal between the two is just to keep the from leaking out from around the T-case adapter. The T-case has its own fluid.
I had a 727/208 combo and when I took it apart the 208 held its fluid when sperated from the auto. I changed to a 435 and put the same 208 behind the 435. The 208 has ATF in it and the 435 has 80W-90. I think a 203 uses 10W-30 or 10W-40, if the wrong fluid is used the certain parts of the 203 won't be oiled properly.
I had a 727/208 combo and when I took it apart the 208 held its fluid when sperated from the auto. I changed to a 435 and put the same 208 behind the 435. The 208 has ATF in it and the 435 has 80W-90. I think a 203 uses 10W-30 or 10W-40, if the wrong fluid is used the certain parts of the 203 won't be oiled properly.
