Welcome aboard.
I can understand the frustration for being hacked. It will only become the new way of American life if we allow it to take over. We'd all love to help you out with that one, but that's another issue for other authorities.
These others are simply trying to offer honest advice. Many have been around doing this for a long time, and are accustomed to the routine of getting all the relevant facts before offering an offhand diagnosis. It's never any fun to give advise which might cost someone time and/or money for barking up the wrong tree.
There are a lot of possibilities, from mounts, drivehshft interference, exhaust interference, A damaged trans, rear axle moving under torque, and many other possibilities.
Does the car still have the original X-frame? That can make for some interesting places for things to rub under load, including the midship bearing and mount.