If young grasshopper were smart he would leave the cab on the frame till last. You should not do ANY bodywork to the cab unless it is mounted to a frame.You cant mount any engines trans or rearend without the cab on the frame.You cant figure out were the frontend belongs with out the cab and front fenders.Heck you cant even figure out were the floor boards need to be welded with out the cab on the frame. No sence in blastin and paintin the frame as you will just be grinding the paint off to build your hot rod anyway.So......you dont really take the cab off till its time to finish weld everything. Done it been there. Its last.