As always, thanks a lot. I was hoping you'd have a chance to write a reply.
The ARP spec for main studs is 60 ft/lb -- no additional turn. I went through the studs and they were all at, above, or very close to that. I probably won't touch the rod bolts.
I saw that Cascade had one remaining AAZ k03 and so I bought it, without really knowing if I need it.
I removed my existing turbo in the process of trying to diagnose a zero-boost condition. It was full of oil and looks very well-used, so I decided to use the new turbo. I had been draining oil to the block bung and always meant to make a drain to the pan, which I'm now finally doing.
But I am still not sure why I wasn't getting any boost. I had been running 10 psi, which dropped to 5. I was in the process of diagnosing this when I had to store the van for a year (I was in grad school in another state). When I came back, on the very first drive, I saw about 10 psi very briefly, and then it dropped to nothing, and the gauge was showing a vacuum (possibly this is inaccurate?)
The turbo wheels don't appear damaged and it seems to spin freely. I didn't see any significant boost leaks and I couldn't find an intake restriction. The wastegate seems to be okay.
Is it conceivable that the bearings are ruined in such a way that under pressure it's locking up?
I haven't heard any strange noises, though I could only briefly and intermittently hear the turbo.
This is off-topic, but I don't want to start a third thread!