Mine was mounted behind the axle, although I don't recall if that was part of the ADDCO instructions or just where it seemed to fit best.
Yes, there is a special bracket where it fastens to the springs. As I recall, the TR4 version was just a flat steel plate with two holes drilled in it. That's what they sent me at first, but my TR3A has the springs closer to the frame than a TR4 does, so there was not room for the end links between the spring and frame. So they sent me the bracket that is kind of visible above, that kicks down so the end link goes below the spring rather than beside it. Anyway, to install the bracket, you have to remove one of the U-bolt nuts, slide the bracket onto the U-bolt and reinstall the nut.
The end links should run fairly close to vertical with the suspension loaded. That shot was taken after the car was wrecked, which knocked things out of alignment to some extent.