Too much mate... What most places do nowadays is u send them your box and they will send you a rebuilt unit in return. Can be anywhere from $600+ depending on which gbox. For a w58 you should be looking down the barrel of a $7-800 swap-over. To get them rebuilt your looking more than that... round a grand. I got priced $1200 for rebuilding the R30 gearbox of mine... but that is around where i live.