I broke the insrument cluster on my 2005 Jeep grand cherokee with v8 engine.( Stopped to quickly with too many 2x4's) I have found a used one. Does the speedometer have to be from a v8 or will one from the 6 be accurate? Will the car then show the mileage of the new odometer and the computer the original mileage? Or will the computer change the mileage of the new odometer to the actual mileage? Will I need to go to the dealer to coordinatwe the 2 mileages?