I was pulling away from a light today rolling about 20 mph when i felt a shudder in the truck, i let off the gas and it went away, kinda felt like i was hitting rumble strips but not as pronounced, I was pulling an empty trailer ( about 7k lbs ) checked fluid not burnt or black , serviced about 5000 miles ago, I dont haul any real weight today probably 13500 total trailer weight and am generally pretty easy on the pedal any ideas are appreciated

 

check u-joints on rear d-shaft first. it's all I got

 

thanks I am due for inspection so I will check that while on the lift