I once called Firm Feel about this very same subject. Sway bar tabs for the Mopar lower control arms.
They have sway bar tabs, but they are only for their own designed and manufactured sway bars.
I don't know how those tabs will bolt on, weld on, or work with a factory sway bar.
Then Mopar used two types of sway bar mount tabs.
One style for the 70-74 e body cars, 70-72 b body cars, and 73-76 a body cars.
The other style sway bar mount tab was welded on very close to the ball joint stud hole on the 72 and earlier a body cars, and the 69 and earlier b body cars.
I don't know what year, make, model car that your working on, but i don't think the Firm Feel tabs will work at all on the earlier sway bar cars.
The Firm Feel bars are located in a different position on the lower control arms.
Just thought that i would give you a heads up this morning, about this issue.
Good luck, anyway.
I just re-read you posting, and your working with a Challenger, so those Firm Feel tabs may, or may not work for a factory sway bar.
There's a pair for sale right now on e Bay. Here's the link to the auction.
http://cgi.ebay.com/ebaymotors/MOPAR-70-...QQ_trksidZp1638