There were a couple of differences, but any Windjammer and Vindicator would use the same mounting bracket and the same lowers. The brackets and lowers were what was bike specific. The exception was the Windjammer V, it used different lowers and maybe brackets as well. The Windjammer III (what I have) was the first using ABS plastic instead of fiberglass ( I think). The Windjammer SS and Windjammer IV had built in turn signals called Leading Edge Lights. They also had an adjustment knob on the dash for the headlight up/down position to make it easy to adjust the headlight for different loads on the bike. The Vindicator was just like the SS/IV but without the built in turn signals. You mounted your original turn signals and stalks on them just like the Windjammer III.
Hope this helps.
MJ