Not that I know of.
Are all the parts on backorder or just one of the three?
The 6112 is very much the only game of its kind in town but Eibach offers a 1" rear spring that is also cheaper than Billstein's. As for the rear shocks, I have been told by a vendor that in addition to 5160, many 6112s are sold with 5100s or Fox 2.0 or Icon 2.0. There is also the Eibach rear pro truck shock.
Of course, if you go 5100, you will have an inferior rear shock not suitable for speed on rough terrain. I know from another forum member that even the basic Fox 2.0 is a massive improvement over the 5100 offroad (I read it has 70% more damping capability). BUT the Fox 2.0 is also reputed to be outright harsh on road on an empty vehicle unless you revalve it. The Eibach Pro Truck Sport has a couple bleed holes to make it ride better over small chop than Billstein 5100 (or 5160 or factory valved Fox 2.0) but will have the speed limitations of a 5100.
Anyway, that's what I have learned: that the 6112 is coupled with all sorts of shocks in the back, even linear ones. I am exploring 6112 with Fox 2.0 with adjusters as an option for me. I have the Eibach 1" rear spring already.