I'm glad things went so well for Joel. I've got to think that the '92 might have a slightly different headpipe. Wouldn't take much difference to make that extra bit of needed clearance.
I had the same results as Larry.
Of course, I have exactly the same year and model.
First car- 1986 300E
1) Removed lower bushing in advance- no go
2) Pushed out upper bushing as well, still not go
3) Jacked up engine on mounts, various tilts- no go
Did not actually unbolt mounts- might work...
4) Detached headpipes and exhaust bracket at transmission, manipulated headpipes about - barely got old bolt out, but pretty mangled.
5) Did not think I could get new top bushing in with bolt without damaging bushing, so I gave up, and removed the rear manifold.
Second car- 1987 300E
1) Detached both headpipes, removed rear manifold, loosened exhaust mount at transmission, pushed headpipes aside, and voila!
This actually went very quickly, since I already had experience from dissassembling the first exhaust.
The 2 advantages here over the 'upside down' method from my perspective are:
1) If the nut falls off for any reason, gravity keeps the bolt in place. You could use a cotter pin or something to get over this fear, or rely on statistical improbability.
2) Torque values apply to the 'nut' in a nut & bolt situation. It is difficult to imagine getting any sort of torque wrench in there on the top with the exhaust in place. This seems like a situation where torque values really do matters, but this may be splitting hairs.
That said, the upside-down method is probably fine, since I tend to be overly anxious about such things.
I think Larry is right that the 'afterthought' pre-cats are the problem. Euro owners on this board probably wonder what the big deal is...
1986 300E 5-Speed 240k mi.