Jeff: The differential is from a 40, for a 40, and it isn't mine. I'm just the guy with the tools.
Christo: Thanks for the reply. This is a contemporary ARB with the current o-ring housing. (looks like the ones on my 4runner) It is easy to pick where to start, but not easy to pick how to get to the other side of the ring gear. In this case, I think the ARB instructions, which do appear to be of a typical FJ40 diff, don't seem to indicate the best way to get from the o-ring housing to the hole I drilled in the differential carrier.
I will re-read the manual in case I overlooked a text description of the routing.