I swapped my gearbox but kept used the drive gears from the old box as I didn't know what the box was from and thought that the gears would be matched to the speedo. The speedo is under reading by quite an amount e.g 25 mph on the speedo is 30mph.
Does the speedometer drive gear match the gearbox or the head unit or combination of gearbox, diff and head unit?
Can they be swapped without taking the engine out again?
Peter