They still make the tabs as I just installed them with my Sport sways about a month ago. The tabs were sold separately from my bars (~$30), but I don't know if they were supposed to be included in the more aggressive packages.
Back to the OP, I would buy new lower control arms simply because I don't know anyone who can weld. You could use this opportunity to upgrade to the FE5 LCA's and bars.
Here is a pic of the FE3 (3rd one down) and the FE5 (bottom one):
As you can see, the newer style bars connect on the outside of the springs which make for a better connection point, and hence the fact that Chevy stopped using the FE3 in 2012.