i have a rear sump of an sc300 for my 2jz swap and was wondering if i should take it to a machine shop to drill and tap the oil return holes or do it myself. since it is aluminum i dont know if it will react different as compared to metal when doing it. i just dont want the worst case scenario to happen where it possibly cracks. if anyone could list what they used to drill the hole and tap the two little holes would be helpful too, thanks.