All Stage 3 t3 turbine wheels same size/trim?
 

I just got a new t3/t4 (w/o turbine housing) with a Stage 3 turbine wheel to replace my dead rebuilt/eBay turbo. I figured I'd drop it right into my current t3 stage 3 turbine housing, but about 1/32" from fully seating the turbine blades hit the inside of the housing. This housing is an OE Mercedes t3 housing that I think was over bored to be a stage 3 (that's how it was advertised/sold to me). It's definitely too big to be a Stage 2 and the outlet measures proper for a Stage 3.

???
My question- Should all t3 stage 3 housings/turbines be interchangeable OR was this just a botched machine job that happened to fit the unknown turbine wheel?

Re: All Stage 3 t3 turbine wheels same size/trim?
 

mercedes has the stage 1½ turbine wheel.
that one has the same diameter at the base of the wheel as stage 3, 65mm
but the exducer is smaller, 1.89" just like staqe 1 turbines.

Re: All Stage 3 t3 turbine wheels same size/trim?
 

Ok. Then it's been over bored, because the outlet is larger than my turbonetics t3 stage 2 housing.