Thanks all. I dunno what number; its just mild steel AFAIK. It was a cutoff from a local machine shop and I asked if I could have it. It weighed 10# to start and now it's probably around 2. I'm still surprised the finish turned out that good since I was told "this knob controls X and this one does Y; don't feed it too fast", then he walked away.
The compressor side of the large one is 91mm, probably off the Garrett that Mike speaks of. It's probably a S400 center chunk and looks like a GT45 ex wheel and housing. Hybrid of some sort.
brandon.