my cab has settled and dropped down to the point that it is crushing the speedometer cable and my 4 wheel drive stuff. is there any way i can jack it up and stick something in there ?

 

How about installing a body lift?

 

If it's rusted bad enough to collapse onto the frame, I believe it's time for a cab swap. Or some serious metal work to reinforce the cab. Sounds dangerous if the cab mounts are rusted through.

What year is your truck so I can move this to the proper techncial section?