Need some clarification on the Mile Marker NP203 conversion kits

[mw67rs]

We I go the NP203 our of the truck. The transmission and engine will come out next. While I have the NP203 out I was considering using the Mile Marker shaft conversion kit to add part time 2wd. I have done some research on the kits they offer and it appears they sell a kit that utilizes locking hubs to achieve part time 2wd and another kit that changes out a shaft assy in the 203 to achieve part time 2wd. I have read that the shaft replacement kit is stronger.

Now my questions, with the shaft replacement kit my understanding is the engine will only drive one drive shaft and some of what I have read makes me think it drives the from drive shaft but I am not clear on that. The other differential and drive shaft will still be driven by the wheels but not the engine. Can locking hubs be installed in the un-driven wheels so they don't take up hp to drive the differential etc?

Thanks to anyone who can help clear this up for me.