2006 Ford Ranger Sport styleside btw.

I've been trying to buy an OEM bed extender on craigslist. I've searched and searched and searched but I can't find the answer to a few questions:

1) What are the dimensions of the OEM ford bed extender? I did measure my bed, to get an idea of what to look for, but this would be most helpful

2) Does the sports trac extender fit or not? F-150 flareside?

3) Is there an easy way to tell apart F-150 extenders from ranger extenders by looking at the pic? Many on craigslist just say Ford truck extender.

4) Is the part number stamped on the extender somewhere?

That's all I have for now, and thanks in advance.