What are you looking for exactly? ford never produced a 8.8 with 4.56:1 stock, so all your gonna find is aftermarket stuff. a detriot locker with same gears would be a even swap money wise. But even if you find someone to swap with you, it would be foolish to just put the carrier and ring gear into you 8.8 with out properly setting up the gear set. this means you will also have to pull the pinion out and swap it for the new one.. My suggestion sell your ARB straight up with no gears (take off your ring gear) buy what ever your replacing it with, (detroit, spool, etc) and put your ring gear on and set up the gears from there, you should be able to retain the pinion depth if you have enough play with the side shims.
