Hi, Durango owners! I completed the 3.7 RWD to 4WD modification. I had not heard about this before, but finally, it was done.

Front diff - 5.7 Durango, same ratio as the rear one.
Front driveshaft - 3.7 Dakota, similar generation, increased length, balanced
42RLE rear tail and shaft from 4wd Jeep Liberty
Transfer case - Jeep Liberty, 242 case
The rear driveshaft has been cut and balanced
Custom automatic rear transmission mount (5.7 Durango + 3.7 Liberty welded together)
Front diff/engine mounts - redrilled 4.7,5.7 Durango

Custom shortened for rear driveshaft from Amazon, which fits 242 transfer case shaft

Manual transfer case shifter JB Custom Fabrication
Front CV axles - 4.7/5.7 Durango

 

Now Durango has these transfer case modes

 

And it's manual shift too. I like it.

 

It was tricky to reproduce the electric shifter, so I went with the manual one. But it can be a good option for someone with good electrician skills.

 

I actually PREFER the manual shifter. A lot less to go wrong, and far cheaper to repair if something does......