I don't know if you have access to the factory assembly manual but it has really good detail on the locations of brackets and number of spotwelds. I agree that cut-off wheel or spot weld cutter would be the way to go. If the existing cab is junk cut it out of the cab with a torch and then seperate it carefully at the original attachment points on a work table. I don't have a scanner but if you send me your address I could photocopy the pages showing the details.
