When driving, get a squeak as the driveshaft rotates

[G-NUT]

I have a 1988 700r4 that I bought recently from a salvage yard. I replaced all seals, filter, installed the Transgo SK-700JR kit. Seems to shift and work great but I have this squeak. It's a 2-piece driveshaft (3 u-joints). I replaced the rear u-joint. Still squeaking. So I got the burn on jackstands, got underneath, shifted to N, and rotated the driveshaft by hand. It's definitely coming from the forward area. It could be the front u-joint but it really sounds like it's coming from the transmission tailshaft area. When I was resealing the trans I had the tailshaft housing off because I replaced its seal as well, and inspected the shaft, bushing, and speedo setup.

Still looking for the source of my sqeak.