[Big Dave]

By now you’ve got plenty of reasons why 4x4 gets worse MPG than 4x2. I owned a 4x4 for 17 years and can tell you that it never came close to the MPG of my 4x2.

Keep the 4x2.

The easiest way to go for hybridization is to shorten your drive shaft and put a double-ended DC motor into the drive line. It could reduce the torque requirement on the engine while accelerating – improving MPG – and it would harvest energy in regenerative braking mode.

Or you could go for the full series-hybrid. Remove the existing engine and simply bolt on an electric motor. Put a diesel genset in the bed and sling batteries where you can.

You can get rear axle gears down to 2.73:1 for S-10 axles.

What diesel are you planning to use? MB 617.952s are commonly set up to use WVO, but will be a real bear to convert into a North American vehicle. Connecting a DIN block to a SAE bellhousing is a challenging machinist problem. Cummins 4BT3.9 engines are easy to come by, run WVO just fine, and bolt right up to Chevy transmissions. They are absolutely bulletproof in this application, but have tow drawbacks: They are a bit tall and they are heavy. Durability comes at a price. The Cummins 4 banger weighs about 750 lb.

Hope your S-10 has a manual transmission. Automatics clutter up the entire engineering process.