Please help!

I have a Sanus wall mount in my home from the previous owner (VMPL-103) that should be fine for my new Panasonic 50" 700, but I don't have the bolts, lock nuts, or washers. Can anyone please tell me which bolts go with this unit? I know I need 4, and I'm pretty sure they are "M8" bolts, but I'm unsure as to the length I need (and I don't want to bore through the front of my new plasma! :)

One other thing... When I remove the discs on the back of the TV covering what I think are the holes for the bolts, I don't see any threaded metal, which I expected the bolts to screw into. I just see a grey plastic piece... Am I supposed to screw the bolts into these grey pieces? Will they hold?

Thanks!

M8----40MM long....if you are using no spacers. There are 4 covers on the back of the bolt holes that come off very easy on the back of the unit. There are threads in there, it is just they are deep.

Thank you for the quick reply - much appreciated! :)