Keep in mind shock valving suitability has a lot to do with the weight of the wheel and tire package, and to a bit lesser extent, the amount of offset on the wheels. Wheels that stick out further have more mechanical advantage over the spring, and effectively lower the spring rate, and require more damping.
A montube gas shock will keep the oil from foaming as mentioned.
Monroe, Gabriel and other house branded shocks are aimed at the cost conscious consumer, and offer a decent ride on a basically stock vehicle. They aren't going to be as suitable for a heavy wheel and tire package on ugly roads, as some of the others.
Factory z71 trucks had Bilstein monotubes stock as part of the package, and I don't recall seeing a z71 with any other stock tire than a 265/75R16.