73 Duster Front Sway Bar?

Is there any welding involved or modification to the LCAs to bolt up an Addco setup on a 73?
No sir. Bolt in kit is just that. Middle mount brackets use the factory bolt holes already in the K member.
For the end link attach point, a L shape bracket attaches at the lower shock bolt. Welding it to the lower arm is a optional / if you have a welder sort of thing.