Could add a sway bar in the rear. They make a bolt up kit. And maybe get an upgraded stiffer sway bar upfront. I believe there is a manufacturer that calls them a muscle bar.
One of the best things I've done to my trucks.
A rear sway bar off of a C1500 SUV can be added. Although the SUV's have integral mounts on the diff, the method of adding that bar to a non-factory equipped truck is the same as the aftermarket versions.
What a good sway bar upgrade for a c 1500 regular cab short bed?
www.gmt400.com
2 wheel 400's came from the factory with 2 possible different size front sway bars.
The front sway bar on a truck with just the single sway bar is larger than the trucks (SUV's) that were equipped with both front & rear.
Sway bar tech is a science unto itself. Whole books have been written on the subject.
For the average guy, the 2 wheel front bar + the SUV rear will make a vastly noticeable difference. The handling of the vehicle will feel much more cohesive. Both ends of the truck, more attached to each other.
Urethane bushings will help to optimize the bar's performance.
Don't be 'tempted' (Damn! I said 'that' word! The O.G. members will know. Sorry, guys.) to go big on the bars. That is, unless you intend to go running around pylons in a parking lot.
Too big on the front & it won't allow for weight transfer. Some weight transfer is needed in order to plant the outer tires. An overly large front bar will result in oversteer. Turn the wheel & the truck wants to go straight, pushing to outside of the corner.
Too big on the rear & the truck will have a tendency to get tail-happy.
Over stutter bumps, rail road tracks, washboard, etc. the back end will want to come around as it bounces.