bed sills on a 42 Chevy 1/2 ton pickup

Hi, I'm working on a 42 1/2 ton Chevy pickup and it is a stepside short bed and was wondering, there are three bed sill crossmebers for that bed and I know where two go, the one in the front and the one behind the rearend that bolt to the frame, but not sure where the three one goes, and does it bolt to the frame too,also do you need to put angle iron on the side of the bed for a wood striped bed, thanks for any input and if anybody have any pictures they can post that would be great

 

check out this link below
http://www.stovebolt.com/techtips/bed/bed_mounts.htm

 

I did check that out, when I got my truck it had three crossmembers plus the rear that hold the bed sides together, so I take it that the third one is the rear one that bolt the side together

 

there is a crossmember that doesn't rest on the ch***is, it just joins all the wood. the bed strips will indicate it's location. when i ***emble the beds i weld it to the bed sides so i can paint it in one piece and then drop the wood into place.

 

thanks for the help