First, many thanks to DonL for finding River City Differentials.
I received my rebuilt diff this week from RCD and it was installed Friday.
A very nice match to the 7MGTE.
First gear is actually usable, highway cruising is very nice.
The pesky rear end whine is gone, but some residual, as I suspect it's
now the drive shaft, or just the noisey W58 resonating through the driveshaft.
Next project: 3" stainless exhaust.