Just got off I-5, was uphill and needed to get in front of the other lane to get my next exit. Was at 4x3 weighing in at almost 18,000lbs when the light turned green, got a rollin and really got into it and BAM!!! Look at the girlfriend with this oh crap look. "Think I just popped my u-joint. " Pulled into 4Hi to get to the side, looked under, looked fine. Back in 2Hi and drove away, no problem since.