The body has been off for over a year. Actually a couple years but I've been working on another bug and trying to ignore the body that was hanging from ceiling joists in the garage. I paid a welder to put new floor pans in but never talked to him about measuring the bolt holes. I just never thought about it. So of course the pan holes don't match up well with the nuts inside the heater channels.
I put allthread in and tried lowering the bug onto the chassis. The front 17mm allthread went in easily. The nut inside the body is loose making it easy to wiggle the allthread to get them started into the holes. But for most of the pieces of allthread they didn't come close to the pan holes. The first two went in but every rod after that missed the hole. Each piece after that missed the hole, getting farther away. By the back two, the holes were over an inch closer to the tunnel. So I marked the metal for new holes then lifted the body enough to drill. Then spent the rest of the day enlarging the holes
So the body is down and it will take time to make brackets that cover the holes I made. A couple of the holes missed the channel or went through the middle. If I hadn't lowered the chassis, I could have welded new metal over the holes but there's not enough room for the mig handle to work. Ultimately I want to remove the allthread and replace with hardened bolts.
I need to replace pans in my notch so when I'm ready I'm going to Borrow your allthread idea (longer allthread) lower the body 2" above the pan line up the holes then tack the pan in place ,lift the body and final weld them in I'm told I still may have to enlarge some holes but hoplefully not that much.