I wish it was wheel bearing. One if the first things I changed out because of the noise, found absolutely nothing wrong with the old ones, changed them anyway, SKF cups and cones. When the grinding started, I rechecked for excessive endplay (still set properly) and they rotated nicely. Have access to an on vehicle tire balancer for heavy trucks (spins up the wheels on chassis) going to spin up the front wheels and see what happens. Gave the bearings the ol' heat test too, all similar temp.

Placing it on stands and running it up would help show if it was from the trans or some strange harmonic showing up in the front, caused by the back? Just willing to try anything at this point. I went looking at a parts car for major component swaps if it comes to it.

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1982 300sd, new project car to restore

It doesn't matter if you know what you're doing, as long as you look like you know what you're doing.

OK, I am convinced you have done the right things with the wheel bearings. Now, I question whether the noise originates from the front of the vehicle or whether you simply hear it that way from the driver's seat.

Put the vehicle on jackstands with the rear wheels elevated and the front wheels blocked VERY WELL.

Have another person "drive" the vehicle at various speeds. Get yourself close to the driveshaft center bearing (do not go under the vehicle). See if you can determine if the center bearing is the culprit. This becomes far more likely if the driveshaft has never been out of the vehicle for service.