Hey Alan,
I just bought front and rear sways from Brothers that are ADDCO's as well. The front is ADDCO #117 (63-87 C10) and the bar bolts directly to the frame without the offset brackets?? I haven't mounted it yet but I am a bit concerned based on your trouble and the different design.
CPP has a technical article for mounting sway bars that doesn't say anything about removing rivets.
http://www.classicperform.com/tech_a...ar/SwayBar.htm
By the way. Brothers uses a Helwig number for their sway bars to trick you into thinking you were going to get a Helwig bar I suppose.
Your thread is very interesting and helpful as you have heard at least 100 times by now.
TR