Folks I'm in NJ looking for anyone who would be selling a white truck cap. Willing to go out of state. I have looked at new ones in NH. They are alot of $ (no sales tax) but before I do that thought I would look at used. I think the dimensions for 09 and 10 are the same...
I have the 6 foot bed on the extended cab.

 

I think you will have a hard time finding a used one, since the 09/10's haven't been out that long and guys who decided to buy an expensive cap probably made sure they definately wanted it before spending the money on it, rather than trying it out and selling it right away.

You definately need to find an 09-10 version though, since our new trucks have a wider tailgate lip vs. the old 04-08 trucks.

also you either have a 6.5 foot or 5.5 foot bed, there is no 6 foot bed.

I check my local craigslist site for F150 parts everyday and I've rarely seen caps on there, and never any 09-10 ones yet. I'm in Pittsburgh, PA.