Is there any difference between the 3500,4500, and 46rh tcases? I know bolt pattern and spline count are the same between the 3, but is there any difference in the input shaft length?

Finding a 3500 tcase should be easy if the 46rh case doesn't fit, but If the 4500 won't accept either case, it could take more time and money than I have for the yard to get the right tcase in.

 

All Dakotas and most 1500 Rams came with the NV231D transfer case. Most of those have 23 spline input, but there was a few with different splines, as well as the Rams came with a larger spline output. Ram 2500 and the few 1500's that came with the NV4500 came with the NV241. Some came with the 23 spline input some didn't. All of them came with the same bolt pattern. In the FAQ there is a link to a list of transfer cases per year and the spline output.