does anyone know how much lockers are for the rear end are and how hard it is to install

 

With your manual 4.6, you most definetly have the 8.8" rear end. As for lockers, Would you want a full time locker or an air activated locker. For a full time locker, I suggest the No-Slip Traction device from Powertrax. It works like a regular locker but they say that it disengages around turns and such. For an air locker, go with the ARB. This gets pricy though. For the ARB, I paid $780, and will not do the install my self. Drilling into the diff cover is required. For the No-Slip, I think somewhere under 300 would be a good price. They say you can install it yourself in a few hours, it just requires the removal of the spider gears. Hope this helps. Oh, you're lucky because no one makes a locker for the 9.75" rear end!!