Monroe 71801 is the air lift version, and I think I won the lottery, getting the last two that Rock Auto had in stock (not that I need them, I only have 25k miles on our vert and without strut issues). They are showing as shipped and in transit, one each from two different locations. You are 100% correct, they are the same base shock (overall length, stroke and body length) with sway bar mounting bracket as the Monroe 71966 but with an air bladder overlay. At the same time I ordered front struts and hardware just in case the same fiasco happens with those. Below are the comparative photos of the 71801 vs the 71966. The 70801 is shown extended, the 71966 is shown compressed. The 71801 is rotated 180 so the pinch bolt divot retainer is not visible).
I am still going ahead with the 73305 (1996 Buick Regal) strut insert concept, developing a mounting tube/capture for that, which will directly fit into the lower control arm. Others on this forum and elsewhere are in desperate need, so it is a worthwhile effort. I have one of the 73305 inserts on order and will create a solid model and get a quote for machining the adapter once it arrives. It looks like Monroe has stopped manufacturing of the 73305 but KYB is still making them and they are available through your friendly local auto parts store. I will try to make this a priority and post updates here.