Anyone using an Addco Rear Sway bar?

Honestly, it sould be cut or adjusted per the vehicle for the best fit. You want to rig everything up and make sure the link is perpendicular to the sway bar and the chassis mount with the cars weight on the rear end.

Position the axle clamps to the sway bar does not hit the rear end during normally up and down chassis movement. It may come close or rub when the car is full up on jackstands, but that is not normal driving chassis movement. Mark that position on the axle with a marker

Then bolt the end link with chassis mount to the sway bar. Move the sway bar up and down slightly off horizontal to see where the angle of the chassis mount matches up to the frame the best. You probably will need to adjust the end link for the mount to mate to the frame at the best angle.

Picture below is with the axle hanging down not suspended.