Rear Driveshaft size question.

[Audiowriter]

I have a 2012 Ram 3500 4WD Crew Cab ST DUALLY (DRW).
I bought it used with 140,000 miles.
However, after spending almost 3 days trying to match up the 3 REAR MAIN driveshaft U-Joints for a DUALLY (DRW)-
Come to find out my driveshaft calls for SINGLE Rear Wheel U-Joints (SRW)
Is this normal or did someone put a different driveshaft in my truck at some point?
(I rebuilt both front and rear driveshafts using my home made horizontal hydraulic press =
A 1.5 ton bottle jack and a piece of a 20 inch wide "I" Beam.)
(Had to use a grinder to cut out part of the old Rear shaft joints...)

 

[Audiowriter]

I got them all done.
2 Moog's and 1 Spicer in the front axle (forget the numbers...)
The rear took 3 Spicer's 5-3206X

 

[crash68]

I wouldn't put it past Ram to use different driveshafts on the same truck layout in the HD trucks also. There are some 1500s that use a single drive shaft when the same truck cab/box layout along with gearing and engine was built with a two sections and a carrier bearing. Same goes for powertrain set ups, the 1500 Outdoorsman is supposed to have the BW44-45 transfer case but some of the '14 model year trucks were built with the BW44-44. (note this was long before the supply chain shortages).