I've had a recent intermittent issue where I turn OD off, accelerate heavily then it will shift into OD randomly. I've had it happen maybe 4 or 5 times i the last few months. Seems to be in speeds about 100. Last time I was at about 125 and just about the time I let off it shifted and the speedo dropped to about 100 for a quick second when it shifted. It's a rebuilt transmission with less than 20k on it. It was put in back in late January.