Rockauto.com has installation kits and ring & pinion sets by USA Standard Gear (division of Yukon Gear) and I have had no complaints with my Yukon Gear/USA Standard Gear setup on my 1999 Explorer over the several years I've been using them.
Generally they are held in good report.
Also on Rockauto.com you can find Richmond gears, but I have no experience with that company or any knowledge of their product quality.
As far as air lockers, you're on your own there - consider ARB, but be aware that many of the Explorer crowd have had ARB's get stuck locked and/or grenade for no apparent reason.
Make sure when browsing Rockauto.com that you select the correct gear ratio; Richmond and USA Standard Gear both have drop-down menus to select your desired gear ratio, 5.29 being one of the several.