Epoxied a thin aluminum plate to the elbow, protected the dash with clear tape and epoxied the underside of the plate to conform to the dash. When set remove clear tape, use double face tape under the epoxy to stick it to the dash. It wedges into the piller but is removable. Spayed it with rubber undercoating for texture and used some gray truck paint that matched good enough.
PS Used the roller end of a belt sander and files to make the top cut out.
2002 GMC 1/2 ton Sierra,4WD, Xct cab, camed, mid-length headers, Nelson tune, electric rad. fan, trany cooler, Heavy 5750 lbs with topper.