Take the strap and gasket completely off and drive a ways holding the column down away from the dash. No squeak then you know for sure. They make oil impregnated webbing you could trim to fit as a gasket, only it might "weep" if left in the hot sun. The steering shaft is one piece and the mast jacket is pressed into the steering box so driving without the brace for a short way is not dangerous. Any change in alignment would have to be where the box mounts to the frame and IIRC the box mount bolts go through both the side and top flange of the frame so very little movement there. I guess you could use shims in the cab mounts to move dash further from frame.

Evan