just put in new tranny( old one shot ),tv cable is adjusted right but shifts into od way too early,any ideas or suggestions,new tranny is stock and no shift kit. shifts into od at like 2500 with slight pedal, or goin easy sometimes at about 1800

and on the highway at 70ish it stays in 3rd,no od

If you haven't done it already, try swapping the governor from your original trans into the new one.