Got the letter and pp stamped
Got the approval letter and my passport stamped with I551 from chicago local office.
They asked for approval letter, I-94, pp and 2 ADIT photos all the previous AP and EADs.
Stamped the pp with very simple looking stamp, took sign and FP.
Now another wait for plastic card....
Good luck for your wait, very soon it will be your day!!
-Pathik