Have had a CAP tubular k member on my 71 Demon for years now...fits perfect....71 Dart has a QA1 ...can not tell them apart if you remove the QA1 decal.
I had a set of CAP LCA's on my Challenger, right up until one of the welds fractured and caused the LCA to distort and lower my car about a 1/2" on that side before I noticed it. Further inspection of the welds showed that while they were decent enough to look ok under the powdercoating, they were far from professional welds.
I also have a set of very recently purchased QA1 LCA's for my Duster. While the design is the same, the quality of the welding is VERY different, the quality of the welding on the QA1 pieces in superior in every way. As in, I will run the QA1's on my car. I wouldn't run a CAP produced anything. And yes, I would have been happy to return the QA1 pieces if the quality had not been up to par.