We have an 06 with new engine(rebuilt) and automatic tranny with 100K miles. When new engine was installed, mechanic had trouble with fluid hose. Long story short, leaked badly, had to be replaced. Ran truck with too little fluid and lost overdrive. Code was tcc or overdrive solenoid performance. Another mechanic diagnosed overdrive was gone, needed to rebuild. Truck runs great otherwise, all other gears good. Top speed 60 mpg, no trouble pulling load (we haul cargo trailers/cars) on 7K lb wedge trailer. Could this be solenoid replacement only or is tranny shot?