Calling Jeep sound detectives: whistle / squeal / whine

Ok since you all are on the edge of your seats, I know, the squeals appears to have gone away. Maybe temporarily, hopefully permanently!

I did two things last night, and I know that is the cardinal sin of troubleshooting, but I did it anyway.

IMO it's down to two possible options:
1. Loose transfer case yoke. The aforementioned salty old mechanic mentioned he had one time heard a similar squeal on the front of a motor. Turned out to be a seal. So before I installed my driveshaft I removed my rear yoke. When I removed it, there was clearly less than the 150 ft-lbs of torque on the yoke nut. There wasn't slop that I noticed though, so I'm guessing this is the issue. Anyway after lubricating the seal I cranked her down to a full 140 ft-lbs.
2. Dry rear seal. I should've installed.the rear shaft and "drove" it on jack stands while squirting the seal with Kroil to see if it's a lubrication problem. If it's a seal lubrication problem then I have to question if the oil pump is working. Which is super annoying because I've had the transfer case out 3 times already this year!

You cannot imagine how nice it was to go for test drive and not have the squeal. If it returns I'll check the nut torque then move to oil pump check.