I do NOT like the Viking extension table I bought for my Platinum 775 so I bought a bigger, better one from
http://sewingmates.com/. When it arrived, the back piece didn't fit right for my machine. I notified them (I think the lady's name was Becky) and she had me take a picture of the back of my machine and take some measurements for her. I emailed her the pictures and the measurements and she sent me a new back piece free of charge and told me to keep the other piece in case I ever bought a machine that it might fit! She also thanked me for the info because she didn't know that what they were making didn't accurately fit the Platinums.
I have been EXTREMELY happy with the new extension table! I even put a night light underneath it and use it as a light box when I need to transfer a hand-embroidery design! :)
No affiliation with sewingmates.com except that I am a very satisfied customer!