[DavidG]

You don't need to hold them in place in the notches in the cowl. You attach them loosely with their screws through the holes in the front lip of the belt rail and drop the belt rail down on the cowl so that the threaded bars fall behind the notches in the cowl. As you progressively tighten the screws the raised portion of the threaded bars fit into the cowl notches and center themselves. There is virtually no side-to-side movement of the dash in the process of tightening the screws.