I bet you didn't do anything wrong. I have a 99 ranger and have had 2 transmissions put in it. Both times the OD off light came on and flashed and shifted hard. The second time it wouldn't even shift from first to second unless I reved the rpm up and then let off and coasted for 2 seconds. The next gear would then engage. Overdrive didn't work at all. After having trouble I did some research and have found tranny problems seems to be a problem with rangers. Good luck!