I have had the truck into the shop and they can't find a problem. the steering used to shimmy when turning toward the right at 50mph or higher now it is doing it in both directions and getting worse.
steering on 1999 Chevrolet Suburban 1500
Something must be loose in the front end and it sounds like it is getting worse. You could try a good alignment shop instead of a general repair shop. An alignment shop may be better at finding worn suspension components.