Here's a cargo net they say fits your bed...Bed Cargo Net with GMC Logo
Another thought...If you're eventually going to be getting a bed cover/Tonneau cover, you might look at the Roll N Lock retractable covers. I have their M Series, and their Cargo Manager. The Cargo Manager looks a lot like your old one, but this one attaches to the bed cover rails and rolls back and forth, with the ability to lock it in different positions.
I really like mine, and it looks like you keep your pickups a long time like I do, so spreading out the cost of the tonneau cover and cargo manager over 16 years...makes the initial cash outlay a bit more palatable.