50-trim Swap?!? Different Wheels?

[Mikelb]

I have two 50-trim turbos. I am looking to swap the compressor/exhaust housing from one turbo (from the oil only turbo to the oil/water turbo). The wheels are different??

I was able to swap the compressor housings, the compressor wheel on the oil/water turbo was smaller, the exducer(?) was smaller than the intake opening on the compressor housing, and the wheel wasn't quite as wide as the other wheel (oil only).

The exhaust housing didn't fit at all. The exhaust wheel on the oil only sticks out further and is much sharper around the edges (clipped?).

I also think the exhaust heat shield is a different size.

I tried swapping the shafts and wheels, but it just didn't feel right. The oil only turbo is in dire need of a rebuild (I didn't think so at first, till I removed the exhaust housing and cleaned some coking up, now it has shaft play). The oil/water turbo is fine, it was just cleaned up and has no measurable shaft play.

What do I need to do to get the housings on the oil/water turbo center housing? What's with the different size wheels? (is that the different stage wheels? 17C 19C? Stage 3? Stage 5?)