I am totally new to thetruckstop. I have a 1991 square body 4X4 Suburban. It's a V2500, so from the factory it's a 350 (5.7) with a 4L80E. I have no OD gear, and already spent over $600 at a local, "supposedly" reputable, transmission shop. Still no OD. Was going to just swap out the tranny with...