After the last post went up I hit the driveway and started working. Disassembly was pretty simple; the bolts holding the muffler to the catalytic convertor had been put on only a couple of weeks ago, and once I had the muffler sitting on the ground, the pipe and catalytic convertor just came right off the downpipe from the exhaust manifold, because whatever nuts had once held those studs fast to the manifold had long since rusted away. I was able to wiggle it out without having to remove anything but the upstream O2 sensor; and then I set to work on removing those sad, rust-eroded studs.
For five frickin' hours.
I managed, after a lot of effort and two trips to the hardware store, to get two 1/4" holes drilled where the studs had once been, and I'd gotten most of the third hole drilled, but I absolutely COULD NOT get the third hole bored to 1/4" all the way through. I tried four 1/4" drill bits.
Og came by sometime around 8-ish and--using the drill he uses daily with one of his 1/4" drill bits--bored the hole through in about forty seconds.
I immediately began reassembly and after I broke one of the brand-new bolts I'd just bought, we took a trip to Menard's for some grade eight fasteners (rather than the grade five I'd found at Ace) and then managed to reassemble the truck.
I took a stab, while it was still light out, at welding the hanger rod back onto the pipe. My first attempt was a cold weld and I knocked it right off with a wrench--not even a hammer--and then I ground back the weld and tried again. My second attempt came out better, much stronger, and off I went to the races.
...finally got everything buttoned up at 10:30-ish. My weld job on the hanger was pretty good but it wasn't all that great, and it broke during assembly; so at Og's suggestion I took a 3" chunk of 2x2 steel tubing, flattened it a bit with the BFH, and stuck it under the exhaust pipe to take the strain off the manifold flange. I secured it with the strapping I bought this morning; it's not going anywhere.
Started the truck, it was about as noisy as it has been; then I realized that I hadn't put the downstream O2 sensor back in. With that installed, the truck is quieter than it's been for a couple of months.
It was a ball-busting all-day job, exactly as I had feared...but it's done, at least well enough that I can get to and from work without risking hearing loss or a moving violation; and now the next time I have a weekend I can work on improving it. Get a gasket between the pipe and the manifold, for example, and maybe take that pipe over to someone who has a real welder, rather than a 110v flux-core rig like mine, which is not exactly well suited for welding thick steel like that hangar rod.
I could not have completed this job without Og's help. And he gave me some safety tips for working on the truck, things which had never, ever occurred to me; so from now on I'll do as he recommends, because he's forgotten more about fixing stuff than I'll ever learn.
Now, I'm going to go do some WoW.