I have an old Graber pickup bed bike rack that I wasn't too enthused about because the fork leg attachment points were not very easy to operate. I bought one of the Thule Low Rider Mounts and mounted it on the Graber rack and was I impressed. Super easy to operate, built heavy duty...and, did I mention easy to operate! I was so impressed that I bought 2 more so I can mount all 3 of our bikes. Now I look forward to putting the bikes in the truck. I can't say enough good things about this mount. Honestly, it's that good.
Disclaimer: Since I already had a bed rack that had fork mounts, installation was relatively easy - I only needed 2 new u-bolts per unit to mount the Thule mounts to my rack. (The Graber hardware didn't line up with the holes in the Thule mount.) If you're going to mount these into a truck bed without an existing rack, you'll probably have to drill some mounting holes...they include a template so that you can mark the holes accurately. Just LOOK (underneath the bed to make sure you don't drill into something important) before you drill.