Hi folks!
Some months ago I bought a -02 Yukon XL 6.0. As it turns out the frame has the same structural integrity as a royal danish butter cookie! Instead of trying to remove all the rust, I was thinking of changing the frame, as I have access to another Suburban. The only thing is; Its a -98 Turbo Diesel
Now for the big question: Can I use the frame of the old car on my newer model? Thinking of cab mounts and engine mounts.

 

Welcome to the forum.

Unless you are able to poke holes through the frame, some surface rust is not going to weaken it. My wife's 04 Tahoe came out of Wisconsin and the under side was totally rust city.

 

Unless you're able to poke your finger through the frame, I wouldn't worry about it.

Is your Yukon a 1500 Denali with the 6.0, or a 2500 with the 6.0?
And I'm guessing the 98 turbo diesel is a 2500?

Either way, you're talking two different platforms, and it's likely that most of the mounts and holes won't line up. Crossmember locations are probably different, too.

 

Even if they were similar, I wouldn't.

Surface rust won't significantly weaken the frame...

if it's in an area of concern, can you weld on some bracing?

You'd have to find a donor frame of the same year/model... most manufactures like to change things more often than they admit, and you may have difficulty fitting it just right...