ECU (Motorsteuergerät) for chip tuning Skoda Octavia 1.9tdi

I'm going to chip my car, but since there is no tuners nearby and I need my car every day. I must get an extra ECU and send this to the tuner. Have the tuner to replace the original chip in the ECU and return it to me). The ECU in my car have the number 038 906 018 xx (xx= I don't remember the last to characters) I have seen a lot of different ECU offered on ebay whit the same number as mine but the last two characters are different. Can they bee used for chip tuning or must I have one whit the exact same number

You need the exact same number including the last two letters. However, in order to work the ECU has to be "trained" to your car (immobilizer). For this to work you need the login codes of your current ECU and the code of the new one (which you don't usually get from those e**y guys)!

Alternatively, let your Volkswagen dealer do the training *before* you send the ECU to the tuner.