4 Wheel drive Hi/Lo clunk

This past couple of weeks I was able to use my 4 wheel drive. While towing my enclosed trailer down a gravel road with 5-10 inches of snow cover when I would slow down and then lightly accelerate, I would then hear a clunk noise from what I believe to be the drive train. I was going slow due to the snow conditions and the sound seemed to always happen during acceleration even slight acceleration. This would also happen in 4 Lo. It got to a point where I was turning off all the traction systems I could to hopefully eliminate the clunking sound with no avail. I did sometimes see a light on my dash quickly blink during or just before the clunk. I did bring my truck to the dealer and was told they could not replicate the noise. However, when I got my truck back I drove behind their shop on some icy road and sure enough the clunk was there however I had no time to go back to the dealer. Any thoughts?

 

I have not experienced that, but I would try to get a video for the dealer.

 

I believe it is just your trucks abs preventing you from slipping.