Alterkation or K1?
The worst part about any of the kits, RMS, HDK, GTS is that they are basically square tubing welded at 90 degree angles to each other with only one crossmember, AND they have the lower control arm cantilevered behind the rear mounting bolt for the original k-frame. I'm not sure what the tubing thickness is, but it is surely flexing a little (or a lot) based on the shape. If it was tied together behind there as a crossmember even if it was removeable it would be a lot better. I can't even think of a modern car that has such a short distance between the front and rear mounting points of the lower control arm.
a removable rear crossbar? great idea!......maybe like this? ....BTW, a HDK exclusive, it has been an option since HDK's inception and a standard feature for almost a decade, along with automotive grade tie rod ends.