all you guys posted and not a one of you steered towards the tech articles and their writeup of eaton roots style superchargers?
Under the "Engines" section of the tech articles there are 5 articles there, 4 are for the 4.0, the first one Eaton M62/M90/M112 has some good info...
1983-2011 Ford Ranger engines and fuel systems tech library covering specs, rebuilds, EFI, carburetors, engine swaps, tuning, and upgrades.
www.therangerstation.com
Ford Ranger owners have increased the horsepower of their 4.0 OHV and 4.0 SOHC engines by adding a supercharger. Currently there is only a kit out there for the 4.0 SOHC engine, and you need to provide your own supercharger. … Continued
www.therangerstation.com
the biggest issue I would think would be either cost if you just want to buy it or how unicorn it would be if you want to scour junkyards hunting for it.