I had a new vcu and prop bearings fitted by bell just over a week ago, they also changed the front diff mount for me. I have the same tightness as you describe, but no other noises, except for a single click noise on the offside rear, when the power goes on after changing gear, or if I take my foot off the throttle and then back on. Could the other diff mounts be worn and causing this click noise?
it could also be a broken chassis mount. check it.