Well, I have measured the turbine wheels between a 351 and the "341", they share the same assembly.
As I mentioned before, even the turbine housings both measure the same, at 9cm2.
The difference is all in the compressor cover, the compressor wheel and the bearing housing.
In fact, even the '01-'02 HY35w uses the same turbine/shaft assembly, but they DO have an oddball exhaust housing that resembles an HX35w, in that it uses a bolted-on back cover, instead of a band clamped cast elbow.
Mark.