A quick modifier to the above.
I found a pic of the 3500 here:
http://www.motivegear.com/tech_info/tranny_guide/tranny_guide.html
It shows the 3500 tailshaft housing is the whole back half so I'm asking the same thing but wondering if the back half or a 4WD 3500 will mate with the internals and front half of the 2WD close ratio 3500.
Also wondering if the 3500 HD internals can go into the 3500 4WD halves.
Seems like it should but you never know!