http://www.rambodybuilder.com/2013/intro.pdf. Its all in here.
The 3500 and 2500 share the same 68RFE. The 3500 SRW has the 68RFE and the Aisin. I thought everyone knew that. There is no reason a 2500 needs the Aisin when the 3500 SRW clone has it.
However my reply was aimed at the myth the 2500 and 3500 SRW didn't share the same chassis/frame.
The link you provided says nothing other than a partial 2500 tow ratings.
For '13 the 2500 GVWR has been raised to 10000 lbs vs '12 2wd 9000 (2wd) and 9600 for the 4x4.
For '13 the 2500 RAWR has been raised to 6200 lbs vs 6000 for the '12 models.
For '13 the 2500 GCWR has been raised to 25500 lbs vs the '12 22000 lbs.
For '13 the 2500 tow ratings had a big increase because of the new truck.
Example; the 2500 68RFE 2wd crew cab Laramie long bed has a 17650 lb tow ratings vs the '12 same truck 14800 lbs.
The same configured 3500 SRW tow rating is 17220 lb which is less than the '13 2500 truck.
Now look at the Ram frame/chassis numbers for the '13 2500/3500 SRW and we see there the same or they were at the time Ram updated the Body Builder website for the new '13 models.