I pulled the rear sway bar off of a Nissan Xterra when I pulled the rear axle for my '50, and was thinking about using it on the front of my '50.
An Xterra is an SUV and has plenty of weight at the rear of the vehicle. A 3100 pickup does not have much weight in the back, so there would not seem to me to be much in the way of excess sway back there requiring a sway bar.
Carl

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission