dear,
same situation i faced yesterday at airport traff. department.
so i can guide you clearly,
you must go to the same police department (old airport) as with in one week time they will prepare your car number plate. no other traff. department can make that as you renewed from airport traffic department, so all record of your vehicle is there only.
if you are going to any other traffic department definatly they will send you to air port traffic department.
do not waste your time just go to airport police department, better go early and provide your new istamara to the police man who is sitting beside the type writer room. then sit in your car and wait, after some time one person will come with your new number plates. he will return you the orignal istamara and the number plates he will give to a technician. so on your turn just they will remove the old ones and fixed new.

i think this is sufficient.