Bob Costas
15 Central Park West
#8C
New York, New York 10023
USA
Additional notes
Turn around seemed to be several weeks with this address. Mine was 60 days.
Used a nice blue Sharpie. Was inspired to send this one in from a post on reddit where someone received a letter back with answers to questions. I had the 1989 Pro Set card and had it in the back of my mind, I was going to go for a TTM once I had confidence in a return.
The other tipping point was seeing him on MLB Carded playing Strat-o-matic, which was a fun watch:
https://www.mlb.com/video/carded-an-epic-strat-battle