Who built the box? If it is a Truck Weld there is a good chance they would have what you need to put one on, I believe they are at the old Washington Truck Rebuilders shop at the Vader exit now. I have never dealt with them them though. There are a few ways to do it, simplest is to have the cylinders on the side of the box but doesn't look as good and they are in harms way. The best way is to hide the cylinder under the lift arms. If you can find one to look at for measurements and cylinder geometry that would be helpful. If done right your tailgate should pin right on. The other thing to decide is if you want to use air cylinders or hydraulic. If you go hydraulic you have to plumb in a diverter valve or add a spool to your dump valve. Either way it is smart to build in some kind of lockout so you can't lift the gate with the latches closed, or have a pressure relief valve set low enough to lift the gate but not tear anything up if the gate is lifted with the latches closed. If it is air it is usually slower to lift but easier to plumb. I don't know what kind of cylinders to recommend for air, but I almost think they might have been regular old hydraulic cylinders on the truck I drove with them. I have never built one but have plumbed them with parts from Columbia Body in Clackamas, they might be able to provide a kit for the lift arms that you could just install. I deal with them alot and they are top notch. A dump truck is twice the truck with one, they are not just for transfers!
