[V8] Still Have Vibration & Noise in 91' V8 Help!!

[Sports Car Workshop]

I have a 91' V8 that has a front end vibration and roaring sound that I'm trying to solve. So far according to recommendations from folks I've replaced what was thought to be a bad wheel bearing, which we replaced and had no effect.  Then we found an inner C/V joint that was very dry - and replaced the whole axle with one we had - no change with a road test. We've changed the diff oil (it looked OK when drained if a little low), and listened with a mechanics stethescope with the car running on the lift right on the diff and it is not making any noises to suggest bad pinon or carrier bearings. We did find the front engine mount to be broken (what's referred to as the "anti-torque" mount) and replaced this forward mount - again with not much change. I took it to a transmission specialist and they suggested it could be the drivetrain is still twisting causing contact somewhere along the line. New engine mounts are very expensive for the V8's vs. the 5 cyl. mounts - and I don't want to put more money into this car if it isn't the root of the problem. The sound it makes is a fairly loud dull roar - not metallic sounding like metal surfaces turning hard like a bad bearing. It's almost like a really bad tire, but I've rotated them front to back. Any help out there? Thanks!

Corey