I don't know what kind of load you are putting in the back of that pickup, but in my experience, nothing will blow out shocks quicker than overloading them.
I carry a BIG load on my Chevy 1500 regularly several times a year, but not weekly or anything like that. My shocks would not take it. Because the job came up only every month or two, I was reluctant to put heavy springs in it. Didn't want to lose a smooth ride permanently just to carry the infrequent extra-heavy load.
The solution I found was from Firestone in the form of "Ride Rite" airbags on the back axle. They are easy to install ( I did it myself!) and I inflate them to 60 PSI only when I need them. The rest of the time, it is necessary to have only 5 -10 PSI in them and they don't take away a nice, smooth ride, which is kinda nice since our pickup gets used for a family transportation vehicle as well.
With that air-ride suspension, I can carry my 1 tonne load load of parts to the electro-platers and back and barely feel that I have a load on.