Unless you ask for 'ready assembled' lock all locks come as 'self assembly to the sequence of the existing lock and each disc is numbered. eg 1,5.3.2,4 etc depending how many discs.
Ask the garage/shop where you got the lock if they have a lock 'Assembly service' and how much and what they need. Or ask them if they will change it for a 'ready made' but they may charge an 'exchange' fee for re-stocking the dis-assembled lock. With a 'ready made' lock you will have two keys, existing for other doors and ign and new (2) keys for boot.
BB, September 2011