Hitch is probably rated at 500 lbs without WD system
How would I know what to look for? According to the owner's manual the 1500 has either a class 3 bumper hitch (I don't have that) or a class 4 hitch (I think that is what I have - it takes a 2" stinger). I guess that takes a lot more than 500 lb. The reason for the low trailer weight on this one is solely due to the 3.21 rear axle. Other axle and engine combinations pull a much higher weight.
I have calculated the various axle weights and so forth and I'm within the limits using the WC hitch. I will confirm this at a truck scale shortly.