I don,t have a listing on your tractor as the parts book doesn,t show it but the 6U tractor which would be about the same is listed as just the tractor as 10,505 lbs. so with the small blade on it you should be well within the 14,000 lb. trailer.
I expect you are well under 14,000 total with tractor, blade and associated dirt etc, but trailer GVWR is load AND trailer. Trailer may be 5-6000 of your capacity. Then you need to look at Combined GVWR in the owners manual of the tow vehicle. tractor and blade at 12,000 or so plus truck and trailer
Look up "D4 weight" on the ACME website and you will get a primer on hauling (legally and illegally). D4 would probably best go on 3 axle single wheels or 2 axle with duals, to really haul it with some margin to spare.
My 7u D4 with a number 4 toolbar blade, 540 rpm pto, and homemade wooden cab weighs right at 13000 lbs. According to my local elevator scales.
Hope this helps.