CerClunk in rear suspension?

I just got and 07 Acces Cab V6, 6speed, TRD/SR5, 39000 mi on it, When driving on bumpy roads at slow or high speeds there seems to be a clunk coming from the rear suspension, im not sure if this is normal or not, but I have visually inspected it and couldn't find anything, I don't believe its the spare tire because it solidly tightened up. its also completely stock, if anyone has in suggestions let me know.

 

Maybe it's the suspension bottoming out on the bump stops? Do you have the rear suspension TSB?

 

not sure, just gonna cross my fingers I do because its passed the mileage on warranty. Does anyone know where the part number is located on the spring itself so i can check to see if its been upgraded?

 

well i'm kinda bummed out because I only have 3 leafs in the spring total, so this probably shows it hasn't been fixed,(unless the TSB for the TRD suspension has different amount of leafs) damn this sucks I just bought this truck with 39000 mi, does anyone know how much it would cost me to get this fixed since it wouldn't be covered under the comprehensive warranty?