ok where to begin more info would be helpful type of ride. for the axle it would be just as cost effective to pick up new axles out of any 4x4 mag or a company like west coast differentials
www.differentials.com as far as a posi goes my personal opinion os go with an eaton true lock more like a limited slip but no cluthes/disc like the factory units. easier on drive line on tires and driveline (unlock around corners locks reast of the time)