This was a simple job on Glock, but not so sure on the Redhawk and didn't find much help in a quick internet search.
Considering replacing 5.5" Redhawk sights (Williams Fire Sights, http://www.williamsgunsight.com/gunsights/pistol.htm, but:
Front: can't tell how I would remove/replace the front sight.
Rear: don't see how removing the blade (only) would allow fitting the new rear piece.
Best to just call Williams tomorrow or is there a quick online reference?