I got the Strange floater hubs on my pro stock chassis---used the 5 1/2x 5 bolt circle--don't even have to jack it up to change rears----also have a aluminum center(don't remember if it is Strange or Mark wILLIAMS) IT HAS THRU BOLTS FOR THE CARRIER BEARIBGS sorry about caps)---I do prefer the nogular iron housings though for drag racing as nothing then lets me down--35 spline gun drilled axles----