The diamond key locks are rubbish man! You can lock any lock with ANY key and most of the time you can use any old worn key to open them aswell.

then theres the fact they are prone to wear, and the petrol cap ALWAYS spins the key inside its plastic so you end up with a key stuck in your petrol cap and an empty tank on the forecourt

Sure the mk4 locks do fit though, the doors are all the same.