I used the address of Silvercup Studios. I sent a LOR, SASE, and 2 photos (one with the four girls and one with Adam). Although season 4 was done shooting, I received a gift and note from a producer of the show. Got a pre-signed (but not pre-printed!) script, and merchandise. So cool!
(I sent Adam Driver another LOR separately, because he had not signed the script).
So, the successes are: Zosia Mamet, Lena Dunham, Allison Williams, and Jemima Kirke!!
Address:
Silvercup Studios
34-02 Starr Ave
Long Island City, NY 11101
Favorite Successes: Italia Ricci, Scott Michael Foster, Selena Gomez, Justin Bieber, Taylor Swift, Jake Johnson, Kyle Jenner, The Goo Goo Dolls, Lauren Conrad, Ashley Benson, Channing Tatum, Jack Johnson, Ashlee Simpson, Britney Spears, Lindsay Lohan, Aly & AJ, Bam Margera, Debby Ryan, Holly Madison, Ian Kinsler, Jake T Austin, Chelsea Staub (Kane), Colton Haynes, Dakota Fanning, Jake Thomas, Jason Earles, Kat Von D, Kim Kardashian, Nathan Kress, Rachel McAdams, Savannah Outen, Shia LaBeouf, Jesse McCartney, Jeremy Sumpter, Mike Wolfe, Jay Leno, Michael Cera, Haylie Duff, Kelly Clarkson
In Person Successes: Cassadee Pope, Taylor Lautner, We The Kings, The Summer Set, Jean Luc Bilodeau, Derek Theler, Chelsea Kane, Melissa Peterman, Tahj Mowry, Alex DeLeon
That's awesome, congrats! I sent a request for Lena Dunham to Silvercup Studios when they were filming Season 3 in May last year, but never got anything back :/
Favorite Autographs: Bill Murray, Carey Mulligan, Neil Patrick Harris, Zooey Deschanel, Michael J. Fox, my "Police Academy" Cast Collection
Most Wanted: Scarlett Johansson, Emma Watson, Lena Dunham, Cobie Smulders, Alison Hannigan, Sofia Coppola, Christopher Lloyd, Katy Perry