Hi mate I just sold my 4.6is there are a couple of things to look for . First the rear subframe bushes only have a life span of 80/90k so check these have been done as its a £400 + job Second is they are prone to gearbox problems at about 100k Three front sway arms can wear at 80/90k I found these out the hard/expensive way. If your going for petrol the 4.6 is would be first choice in my opinion as its more powerfully than the 4.4 and less to insure than the 4.8 . As for diesel it's for buses, taxis, and lorrys !!!