Time to update... I did progress a little more. I got the core support body worked and sent to paint. Hopefully I'll get that back soon, or maybe after I get back from vacation.
I've also got the old crossmember out
...and the new one painted
This is a POL unit, which came with hardware. The instructions do not say anything about drilling, but the bolts that are supposed to hold the crossmember in are definitely too large to put into the stock rivet holes. I'll have to drill them out for the 1/2" bolts. I even tried buying 7/16" hardware, but it was still too big. The 3/8" hardware they sent for the trailing arm mounts are a bit too loose to use in the stock crossmember rivet holes, so I'll have to drill the holes larger anyway.