I have never in my life seen a prong rest that wasn't adjustable. Even if it takes bending the prongs with a pair of pliers, they can all be adjusted.

Anyway, as I posted on your thread on the hunting forum, your biggest problem is your arrows are underspined. Underspined arrows will never tune or group together, even with field points. Put broadheads on the blasted things and the problem is magnified.

Forget the rest and put that money into arrows. 5575's are just what you need, if you want to stick with GoldTip XT's. NOTHING is going to work for you until you get stiffer arrows.