I like this 2009 response from enginejo (jalopyjournal.com):
Shocks are most effective when mounted the same as the direction of deflection. So in theory, you would mount them vertical. But if you do, they do not resist axle windup forces created by acceleration and braking, or side to side forces from body roll. Angling them forward helps resist axle tramp caused by acceleration, but not braking. Staggered shocks, one forward, and one back, resist both braking forces, and acceleration forces, as well as controlling bounce in the springs. And angling them in too, helps resist body roll, although the current thinking is to control body roll with a sway bar.
Another reason for angling the shock, you can mount a longer shock in the same vertical space, so for every inch the axle moves, the shock may only move 7/8". This does make the shock less effective, but you can use a stiffer shock to compensate. On a light car, where most shocks are too stiff to begin with, this can work in your favor. This allows using a longer shock on a lowered car without limiting axle travel like a short shock would.
The closer a shock is to the wheel it is controlling, the more effective it is, because the leverage of the wheel is less against the shock. When a wheel bounces, the fulcrum of the lever is actually the opposite wheel.
The more a shock is angled to the direction of the force acting on it, the less effective it is. Vertical to the force, it is 100 percent effective, 45 degrees to the force 50 percent effective, 90 degrees to the force, 0 percent effective. Most shocks are calibrated to be run at 15 to 20 degrees from vertical.
My input:
In a nutshell, one has to choose. I would think an AD farm truck would be designed for hauling and not jack rabbit acceleration and expressway stopping.
I did read it is best not to tilt the shock in two directions. Example forward and inward.
