In my case, I had the unrestricted SS Card from the very beginning. So I did not have to apply for a new SS card after getting my Green Card. However, for my wife's case, she used to have a restricted SS Card (Not Valid for Employment written on it) and we had to apply for a new unrestricted one after her I-485 was approved and passport was stamped. We went to the SSN office and they accetpted the application but gave us a receipt stating that after they get the clearance from the DHS, they will send the card to us within two weeks. When I asked how long such a clearance will take and they said about 1 month. After about a month we did get a notice from the SS administration that the new card has been issued and will be mailed to us within a week. We received that card in about week after receiving that notice. So if you have applied for a new SS Card, it may take about 6 to 8 weeks to get it. Rest assured that the issuance of an unrestricted SS Card will need DHS clearance and the SS Card willl only be issued after such a clearance is issued in your favor.