OK. Fair enough!
In this case, it very well be the wrong application. However, it is not uncommon for the same load capacity etc to be created different ways. For example later Wagoneers got springs with more leaves for better ride quality. As far load load carrying capacity and spring rate - they were the same as the springs on the earlier years.
Key things to look for are front and rear segment lengths, spring eyes are correct, and then if there were options, the correct rate and arch so the spring is flat at normal load. That way the axle steer helps in corners. The wagon has more wieght on it the rear springs, and they also must also assume it will have cargo or rear passengers.