Pleas can anyone help me,I used to run a 1992 4.2 diesel land cruiser auto,fantastic truck couldn't fault it,until it was wrote off by an even bigger truck, iv now bought a 1942 international harvester 3ton military truck & it has a 80's series 4.2 turbo deisel land cruiser engine & box in it, with 5 speed manual & transfer box from about a 1992 ish truck, all gears & transfer box gears are standard, the rest of the truck is standard diffs & axles, witch we could never get new diffs for (because of its age & rarity) !! My dilemma is the truck cruises at about 40mph at sensible revs, I need it to cruise at 50mph at the same revs, the truck pulls away easily in 2 second gear, if it's got a very slight down hill it pulls away nicely in third !! So we have plenty of power & holds the hills without dropping gears early !! The height of the wheels is 39 inchs tall, where as the standard land cruiser wheels stand about 30 inches tall. Im thinking can I buy a kit for the transfer box to give me more speed with the same revs !! Please please help im ripping my head to bits here !!