can you tell me how to put cab corners on i have a 1987 chev truck i do have a mig welder i am not to good at it yet still trying.do i overlap it on the truck or do i cut it even with the body or do i slip it under the metal the cab corner i bought dont seem to fit perfect what do i need to do. there is already and aftermarket door on when i bought the truck that dont seem to fit right and when i slip the cab corner over the rusted corner and close the door the seem between the door and the cab corner is to tight. need help. and before i weld it on do i prime the back of the cab corner thanks paul