the more i look at it somthings is not jiving with all of your parts, and the supposed setup.
the out put shaft for a 4x4 th400 sticks out of the housing about 1", with the 205 input and the thickness of the adapter they would never be albe to bolt up tight.
a th350 is about dead even, which does make sence when you look at the stock adapter and input on the 205, they would engauge properly when bolted together. everything i have seen and read says that th350 used a spud shaft to mate with the 205 this doesnt need one.
there are some odd 400 and 350 s that use weird shafts but they have different names, do some searching or get ahold of grumpy old fart he could give the best help.