As 4x4 Junkie states, the diff is offset in the rear for DAMNED GOOD REASONS.
(Driveshaft Vs gas-tank clearance as a start)
Another reason is that due to "legacy design issues" in the Cologne engine family (2.8, 2.9, 4.0 (OHV) & 4.0 (OHC)) the crankshaft is not technically centered in the engine block
This is all based on the fact that the ORIGINAL FORD COLOGNE ENGINE was not a V6,
but was instead an inherently unbalanced 60deg V4 engine, that used a balance-shaft to keep it from shaking the car it was bolted into to pieces... (a 60degV4 will vibrate in all three axis)
So when redesigning it as a V6 the crankshaft was offset, this was eventually taken advantage of after the introduction of the 4.0OHC when once again SOME variants of the engine were equipped with a balance shaft....
But when Designing the Ranger Ford always planned on using the "Cologne" 2.8 V6 so offset the driveshaft in the original chassis, transmission and rear axle designs
This is why the original Ranger Manual trans the "Ranger5" or T-K5 transmission is "canted" towards the drivers side so to angle the shifter towards the driver and the output shaft to the passenger side to prevent rear driveshaft phase vibration issues...
the idea here is that to avoid vibration with simple "Cross-joint" drives-hafts you need to keep the transmission output-shaft and the differential pinion-shaft parallel in two planes.
Offset either vertical or horizontal of more than a few degrees will create vibration that is hard to eliminate...
At this point I'll say that Factory Engineers are a bit smarter than most people will
give them credit for...
AD