'55 bed cross sill mounting question

[mygirlz55]

When we purchased the truck, there were alot of things not bolted down etc. The bed was one of those things. There wasn't any wood and the cross sills weren't all bolted down.
Anyways, I'm at the point of assembling it all and would like to know how the cross sills are supposed to line up along the bed.
I know where the front and the rear ones go, but the other two that I have are the ones in unsure of. One is shaped differently than the other. Also , how do the bed sides connect to the cross sills?
Sills bolt to frame. .. then wood lays down. .. then bed sides sit on top of wood and bolts through to cross sills?
Any help would be appreciated. Pics would be even a bigger help.
Thanks