I thought this would be obvious just from looking at the final cage: there is no room. The layout and size of the TR-4 final stage is quite different from the T-4X series. As far as dimensions go, they are both the same height but that's it. T-4X/TR-4: width= 6 1/2 vs 6 3/4, depth: 4 1/2 vs 5 3/16. Three won't go into two.
