Whats the difference?

My alarm module has packed in today and the central locking has stopped working. I have gone through my box of spare parts and found an alarm module which is part number AMR 2109. can anybody tell me if this would work on my car and what the difference is between the existing part AMR 2106 and the higher numbered replacement I have?

Cheers C

Speak to Rimmer Bros - they only have the AMR2109 on their books - so they mite be able to tell the difference.