DIY  Wooden Pickup Truck Cargo Divider

This pickup truck bed divider is inexpensive to make, easy to build, it's relatively light and only takes a few hours to fabricate. Here's a few photos, in case you were thinking of building a divider that's a little different.
Pickup Truck Bed Divider DIY Wood gmc Sierra Silverado Ram F150

This conventional 2x8" board didn't provide enough room in the area between the rear slots of the bedliner and the tailgate. Anything that didn't fit needed to be lifted over this one - kind of a pain with the tonneau cover in place. This old divider isn't used anymore, just placed here for the photo, however you could use both if needed.
Standard Pickup Truck Box cargo Divider

A couple of 2x4s, a 2x10, some 2.5" deck screws and some glue are all that's needed. 
By using the front slots in the trucks bedliner, there's not that constant pain of lifting objects over the traditional rear board using the rear slots.
This design also creates 4 extra bonus partitions up front to keep things from sliding around the front and middle of the pickup truck box. The small side pockets hold two anti-freeze windshield wiper bottles each.
Pickup Truck Bed Cargo Divider made of Wood
The slots in the trucks bedliner are slightly curved at the bottom, so some fine tuning of the 2x4 with the belt sander was required for a "very" tight fit. Do this board first as you will have to adjust it a few times before starting the assembly.

A couple of dado joints in the 2x4 increased the gluing area and then everything was glued and screwed.
 Pickup Truck DIY Divider Cargo Groceries

Drilled 3 large holes and routered them as well as routering the 2x4s to lighten everything up a bit.
Drilled smaller holes for bungee cords to go through (middle) and even smaller ones (top) for bungee hooks to insert into.
Two eye-hooks were added after this photo was taken which seem to get used the most (see first photo above).
Sprayed "Rubberized Rocker Guard" to match the bedliner and waterproof the wood.
 Pickup Truck Parts for Cargo Divider gmc Sierra Silverado Ram F150

Just another photo of the completed unit placed in the truck.
The pickup truck bed divider is surprisingly light yet stays in place even over the roughest roads and potholes.
Pickup Truck Pickup Truck gmc Sierra Silverado Ram F150

Plenty of room for cargo and tools now, and no lifting heavy objects over the traditional rear board.
All of the rear cargo can still be reached from the tailgate without having to use a pole etc. (This looks like a crazy long reach because of the wide lens on the camera, see photo 3 above for a better perspective.)
The 2x10 can always be moved towards the back of the truck during construction for shorter arms.
Added some ~8" strips of 1/2" foam (see update below), double-sided taped to the bottom of the 2x10 to reduce a clunk when going over sharp bumps. The semi hard foam took on the shape of the bedliner floor, reduced any noise and still lets water drain if necessary.
DIY Wood Pickup Truck Divider Pickup Truck gmc Sierra Silverado Ram F150

It's been years ( 2014 ) since installing this divider and I've been noticing a thump going over sharp bumps and potholes. It sounded almost like a loose exhaust hanger. Most people wont care about such noises, but unusual sounds coming from my truck irritate me, so I added this quick fix.

I wanted a solution that would not require tools to remove the divider. I ended up using two simple wooden struts that use foam (a cut up "pool noodle" from the dollar store) for tension and suspension. You can see them here at the heaviest part of the divider.
Truck Divider hold-down 

Here you can see a close up of the strut and foam. Cut the strut to almost the exact size and angles required, but leave it a little short, then use the foam to make up the difference and keep the strut pressed tightly to the underside of the box rail. Caution: Be careful not to make the strut so crazy tight that it deforms the bed rail.

The foam will wear out over time so a few wraps of electrical tape will help slow the wearing.
Several wraps of tape on the strut where it touches the paint under the bed rail will help save the paint from damage / rusting.
To install, press the strut into the foam at the bottom, then angle the strut until it fits under the rail, then slide the strut back along the bottom of the rail until it is straight and the foam is compressed and tight.
To uninstall, just give the strut a knock towards the front of the truck and it will fall out.
Truck Divider wood  ...Get Greedy