no way your in overdrive and running at 3,000 rpm's doing 70 mph. its really a 3 speed trans with a over drive, why they call it 4th gear ill never know. the 4 th gear hub splines wear off and bye bye overdrive. like posted above, its fixable.
in o/d at 70 im only doing 1800 to 2,000 rpm
i lost 3 rd in my trans, so i had to nail it to 45 plus mph in second gear, then let off the gas and let o/d catch then i could drive at highway speeds like normal. sucked not having a passing gear lol