This kit will fit your front axle OK because it picks up the axle mountings between the springs; the spring spacing on your '46 is the same as on the later trucks.
If you have the front crossmember in the same place as the later trucks, the two chassis brackets that come with the kit should fit as well.
Here's a photo of this swaybar fitted to my '50 truck to give you an idea of what it looks like installed.
http://i103.piczo.com/view/3/h/b/5/2/u/p/w/0/w/z/t/img/i279279759_79304_5.jpgStuart.
