The 3rd gen 3500 DRW Dodge has those big 9350 RAWR.
Many DRW Dodge trucks rear axle of that era may weigh in the 3500-3700 lbs which leaves around 5500 lbs for a payload.
Just like any trucks on the road separate front and rear axle weights are necessary so the owner doesn't over load the trucks front or rear axles. A single gross weight won't tell you if a axle/tire is over loaded.
The 3500 DRW Dodge is one of the more popular trucks for LTL commercial haulers that carry loads up to max axle and do it safely for several hundred thousand miles.
Dodge gave you a truck with certified axle ratings. Use them. The rest of the trucking world on the road does.