I found a seller on ebay who has lots of listings for repairing all kinds of Macbook Pro logic boards from 2008 thru 2012. I have a 2011 MBP with dead GPU, so I need to get that fixed. I haven't bid on an auction yet. I sent him an email asking him to confirm that he has AMD 6770M with 1 GB RAM GPU chips. I told him that I have a Late 2011 15" MBP with 6770M GPU with 1 GB RAM. He replied asking me to give him the logic board part number. All I could find out is that the part number is A1286, but apparently all 15" MBPs from 2008-2012 have part number A1286. I emailed that to him, then he replied asking for my serial number, so I gave that to him. Then he gave me a vague reply saying he could fix the board, but he still didn't confirm that he has any 6770M GPUs. I don't want him to install a 6750M GPU by accident. I have seen this seller recommended on this forum before. He seems to be offering the best price I can find for the GPU replacement. But why can't he answer the simple question of "Do you have any 6770M GPUs?" Seems like a big red flag that he doesn't know what GPU model numbers he has in stock.