Probably a lost cause but...

according to USDA 9-12 month is probably optimal. May still be edible but possibly not the tastiest.
USDA Food Storage

My feeling is this will have a freezer burn taste. You'll probably smell it when starting to defrost. My advice in the dumpster.
I have kept freshly butchered turkeys vacuum packed in my chest freezer (not a frost free freezer) up to 18 months one time without a problem but I try to use my turkeys within a 12 month period. These fresh butchered turkeys from a turkey farm are only available to buy one week a year which if why I have 5 of them in the freezer after that time. That said I think personally any frozen store bought turkey should be pretty much be defrosted and cooked very shortly after getting it home but hem I'm rather picky about my meat and don't like how meat is treated in transportation and in the stores but then not every I lucky enough to have alternatives for purchasing.

I say thaw it out see what it smells/looks like.

If it doesn't smell like the freezer and it isn't freezer burned, go ahead and brine it and smoke it. What have you got to lose?

I'd take this on as a project, but I wouldn't plan to serve it to company right out of the smoker.

It will surely depend on the freezer and settings. Some cooks like a storage freezer to be around -10 to-20 in temp, it will length the time of quality food. Now others will just try to conserve energy and not keep their freezer as cold.

It could be a determining factor also, if you have a frost free freezer?

Yeah, I'm with the others. Thaw that thing out and see if it is freezer burnt.

quote:

Originally posted by shadowrider:
Just how long will a turkey breast stay good in a deep freeze?

As said in a chest type deep freezer and it was kept in the very bottom. It got buried, that's why I forgot about it. It's a Honeysuckle White, in original package. "Best by" date was 1/10/2010. I'm wanting to smoke it, but I'm thinking that the dogs won't even want it. Should I even bother to thaw it? Or just pitch it into the dumpster frozen?

Is it worth the worry? Get another while you still have time.