Never got to the point of installing the metal blocks from the kit, I go to test them out today and they wont even fit. Anyone have this issue? Could it just be my bed is sagging?

 

They're meant to be put in when you install the lift blocks. Your picture is awful, but you'll need to loosen the bolts in order to get them between the frame and the remaining crossmembers in the bed.

 

I got a better picture, its about 1/4 inch too tall. If the blocks themselves are 3 inches shouldn't this gap also be 3 inches as well or is the bed just sagging that much?

 

More than likely it is sagging if you've put weight in the bed without them installed. As I said previously, loosen the bolts for the plastic pucks, lift the bed up enough to slip the metal blocks in, and then set the bed back down and re-tighten to spec.

 

Thats odd because its only been on this truck for less than a year and the only weight that was ever in it was from me walking around in it once or twice.

 

Trust me, that's all you need when the crossmembers aren't supported.