Is the rear axle on the SRW and DRW models the same except for length?

I noticed on the Dodge site the SRW truck is rated at 10200 lbs. That is about 2000 lbs lighter that the DRW. If the difference is just the tires then that can be corrected with 19.5 inch wheels and tires. If they change the rear axle then the SRW is a joke with such a low gross weight.

 

My 07 brochure says the C&C dually axle is 11.5" so it's probably the same as the 3/4T AAM. The 3500 C&C diff housing didn't look any bigger to me. Craig