Sway Bar Mounting

[T and S]

I am installing my sway bar I picked up on my 1966 C-10, but....
I thought (first mistake) the frame brackets mounted where the rivets are for the cross member under the rad., and then drilled 2 more holes. But with my brackets mounted there, my bar is into the springs maybe 1/2 to a full inch, so I know that can't be right. Their is a slotted hole in front of the rivet holes, maybe 4 inches or so and I am thinking that's where the front of the bracket should be mounted. If anyone would have a pic or suggestion it would be greatly appreciated, thanks in advance !!!