I'm up here in the great, salty Northland. I haven't run the car in the winter, let alone rain, in 30 years but the damage has been done. 189,000 miles on the car. The obvious problem is that the rear bumper wobbles side-to-side. The frame looks OK but the mounting "channels" at the rear on the underside of the body are shot. Like paper thin and crispy. I've spent a few minutes under the car and it's not clear how many are good and how many are bad. I'm thinking to expect the worst. I've talked to a body shop that's willing to take this on. I think the cost of replacing the mounts might reach the value of the car. Not like I didn't do that on the last engine build but that seemed like a better use of the money. It's hardly a show car. I've used it as a driver all this time. Still put regular plates on it. Looking at it, I gotta wonder how this repair could be done. The obvious, and most $$$, approach is to lift the body off the frame, fix all the mounts, and re-attach it. Hmmm... I'd expect 30 or more shop hours plus parts! Any ideas on how to do this? Is there a source for replacement body mounts? Looks like that'd be a channel with a nut welded in. I've found the rubber bits at a few places. Any suggestions? Something like: https://www.opgi.com/riviera/BR01853/ I've never welded but this seems to be the job that forces it. I don't have a hoist, either, and I'd be rigging something to hold the body up while I raise/lower/raise the frame. Thanks guys!
Have you pulled the trunk lining and sound deadener up in the trunk to see what the floor looks like. You must inspect closely to make sure you understand the full scope of work. Often this kind of rust turns into a huge can of worms. Its hard to say without seeing it but it sounds like you may be better off buying a rust free section(s) from a parts car and weld them in. There are no prefab mounts/floor support sections in the aftermarket. So you either fabricate from scratch or find a dry car and have the pieces you need cut out and shipped. Might seem expensive but you save many hours of labor fabricating. If I was paying standard shop labor rates I would choose to get rust free metal. I strongly advise against lifting body from frame. Massive job on a rusty car. oldbuickparts.com has individual rubber cushions.
Yes, I've looked in the trunk. The floor looks OK. Or, at least, "good enough." I know this could really get out of hand. I'm just not sure how to get the clearance to work on it. I'm reminded of a friend who moved the engine from one car to another and called that "re-doing the body." Seems much more practical.
