I've done a speedo swap twice already. One in my 95, from a 115 cluster to a 150 cluster, and one in my 93, from the "yellow" cluster to a '96 "white" cluster. I swapped the odometer units in both and the mileage stayed the same and continued counting right.

Someone from Europe asked me to find him a Firebird 240 KPH cluster to swap his current 175 kph cluster out. (his car is a Canadian import)
I think finding a MPH cluster will be easier for me, but the question is... if he swaps his odometer unit out of the KPH cluster into the MPH cluster... will the odo start counting KPH or MPH?
If I remember correctly, the odometer unit includes the little (stepper?) motor with it, so theoretically, it should continue to count KPH. Am I right?