if the ecu has same part no with mine , will be ok to switch between them ? and what if the ECU come from an vw with same part no ... i know has to ahve same engine , Mine is ATQ 2.8 , but not sure what engine had the other ecu, but have same part no ......

 

Not clear about the reason for replacing the ECU, could elaborate?

 

The ECU will need to be coded per the Audi shop manual CD. You will need VAG-COM to do this. The ECU from the VW may be coded differently.