My challenger runs great now with one last bug to work out. At about 30mph or so, I get a whirling/slight vibration noise/feel feel that I think is driveline related. Its like a thummmmmm space thmmmmmmm space thummmmmm, and as the speed increases, it becomes more periodic. Since the car is a complete restoration, everything is new or replaced. One thing I noticed is that the square washers on the transmission support bracket are positioned on the outward side of the bracket and not between the transmission and the bracket, so they are not acting as shims. I dont have photos of this area before I removed them so am not sure if I have them installed correctly. My shop manual shows them as being installed the way I have them. Can anyone confirm if these square washers are correctly installed? Could this be related to my problem?
Any other ideas/suggestions?