Strange new issue towing
 

Thanks in advance for any advice. Truck is 2007 2500 5.9L 2WD mega. I've had since new, 276,000 miles. The past two times I've take out my boat, my truck has stalled out on the ramp spinning the driver side tire when pulling the boat out. Boat and trailer weights 6200-6300lbs. The ramp is damp/wet but this is the same ramp I use 75% of my boating time and I've been pulling this same weight of boats since I've owned the truck new. The truck has NEVER had this issue whether the ramp was wet or dry...not even close. Any ideas? Rear end/differential issue? Thanks again.

If it has a anti slip differential, something is out of whack.