Here's mine. This is first mod I made. Just got my truck last week and needed something quick for a trip this coming weekend. I bought a four rod holder from the local Bass Pro Shops
and painted them black. (They didn't have them at the Walmart by me, so I probably over paid @ $25.) I just bought some stainless steel hardware at Lowes
to mount it. I got one inch washers that I used on both sides. I angled the one end into the utility rail system and popped it in place and used a wing nut on the other side to secure it. It's really easy to remove when not needed.
You can see it here before mounting where I screwed corks to the bottom. These keep it from bending in toward the bed wall:
Here it is pre-assembled and ready to be mounted:
Here it is mounted. It's a little off center because the corks needed to go into the indentions to fit. I may cut the corks to allow me to center if it starts to bug me.
Here's the hardware I used: