its unbelievable how stuck those perches can get. Some move easily and some feel like they're welded to the body. I've put them on a 20 ton press and couldn't get them to move. Judging by the corrosion i think you're going to have a tough time getting it to move. Best bet is to take it off, pull the spring and flip it upside down and let it soak with PB blaster or some other rust cutting fluid. Use a wire brush to clean out as much as you can and keep soaking it. And yes, the sticker will make things worse too so if you can get that off, thats one less thing to bind you up. Its just going to take a lot of banging with a hammer, PB Blaster and probably some heat to get it to move. I can't figure out why Ford and Fox thought a raw steel lock ring in against a an aluminum shock in the most corrosive place on the truck would be a good idea. When i rebuild shocks i cerakote that lock ring to keep the corrosion down.