Bumping this conversation...
If I'd like to leave the 4 speed...and add overdrive what are the options. Just thinking about this now as my ears were ringing after a 25 minute highway drive.
(Yes, I know I need that tar paper stuff in cab, and I have a 5.17 rear which is probabaly not made for 60pmh, and I have the bais plys on split rims...so maybe this isn't the answer, but was just wondering.)
