The short answer is that you aren't going to find these. This is a 6 year old tv model that has had all of the "case goods" such as the speakers, stands, etc discontinued long ago.
The part number you mentioned is incorrect though, and there are 2 separate parts, a left and a right.
I have searched a dozen sources and none have the item available. There is one source that claims to have them as a special order item, but they are about $45 each, another source says they are in stock (online inventory is always questionable though) at $65 each.
Given the cost of the part, and the overall low power and poor sound quality you'll get from them anyway, I'd highly recommend foregoing the internal speakers entirely, and instead hooking up an external sound system. You can get a soundbar for under $100, which is less than you'd pay for 2 replacement speakers and still have far better sound in the end: http://amzn.to/1LGyeQ8
If you still prefer the original speakers, let me know and I'll send along links for them.