OK, a friend has a brand new NoSpin locker he wants to sell. It was in his shop when he bought the place. The hand writing says GM '87 duallie. Assuming the duallie was a 14 bolt FF (did GM use anything else?) would it fit a regular 14bolt FF? My ancient GM parts manual shows different part numbers for the dually axle, but it "looks" the same. Real trucks don't have spark plugs!