NP435 Trans Swap Help

1984
The cab/front clip has the VIN on the dash, door jamb, under bottom of hood, and it's from a rust free 2WD automatic 1/2 ton, according to the VIN, and iirc the 5th digit decodes to 4-5k lbs.

Cab has the 'small' trans tunnel, which would be for an auto.

The bed is from another truck, as well as the chassis, Dana 44 and Dana 60, 8 lug wheels, 318 4bbl, granny gear manual trans.

So what's the difference between a W250 and W350?