I have done a shackle flip to a TF rear using donor brackets and made hangers for the front, motor mount cross members, tranny cross members, etc. All bolted. I fail to see exactly what your problem is or what you are asking? Are you bolting a cross member back on? or a cross member AND a shackle bracket/hanger? Whatever you are doing, just bolt it together. No need for rivets. Line drill if you want parts to be super aligned, but not necessary. That geometry is not Space Station quality. But again, I don't actually know what you are bolting and why you are worried about threads/non threads in a hole. There are several reasons the factory used rivets. Cheap, fast (at the time), strong, won't come loose (a bolt won't either) and when you have parts made, with several mounting holes, made at different factories/vendors on different machines and the location of those holes have a tolerance, holes must be larger to accommodate that tolerance. Rivet holes can be line drilled and/or the rivet swells to fill any mis-alignment. This aspect of riveting is more important on precision parts. These are not precision assemblies. Bolting is OK. If an assembly is not line drilled/match drilled there will always be larger holes than the fastener, even when riveting. Riveting a truck frame would take knowhow, the proper big solid rivet and some honkin tools. Some of which most of us don't have. I sounds like you have a normal situation where you hand bolt everything together, check for straight, plumb, function and torque'em down. Grade 5 bolts with flat and lock washers. All above is my opinion using some knowledge and experience. Others have different knowledge and experiences.
