as the subject line says, i've got a '92 with some frame rot. i believe it's about time to replace the clutch, which requires removing the crossmember under the transmission. the problem is, that's where the rot is. and be warned, this is about to get sorta confusing:

should i go ahead and make (or have someone else make) new framerails to go over the old ones, then use a good GM crossmember? or, i was also thinking about (and this would be considerably cheaper) completely going AROUND the compromised area, making a tube-style subframe and just welding the new stuff to the good portions of the existing frame, then making my OWN crossmember?

buying a new car isn't a financially feasible option, so if that's your solution, i'm not interested. i mean, aside from the frame damage and the fact that i've gotta replace the clutch, the car's pretty neat...

 

I believe that the car will be stronger and safer if you cut out the rusted out areas, and weld new metal in it's place, maintaining the original structural integrity of the car body.

 

Hey, just thought I'd say I'm kinda in the same boat. I have a 91' looks almost exactly like yours, but no t-tops/ rims. It has some what the same rust problem, and could use a clutch kit/ tranny rebuild (t-5 trans). Mines more of a floor problem though, not as much anything else. I too, am gonna try to find ways to deal with what I've got because of money. I'd probably do what Ws6 said though and cut the old areas out and weld in new. Sorry, I know I wasn't any help, but I'm more supporting you, lol. Good luck with it.