Anyway, if anyone who is reading this doesn't understand how the differential works in a vehicle, but has always WANTED to understand, here is a great video clip which, although made decades ago, explains in very clear terms what goes on inside that big round thing that you see in the middle of the rear axle (and/or front axle, on 4-wheel drive vehicles) of a pick-up, car, truck, etc.  I know how differentials work, but this video was fascinating even to me, so even if you're not into cars, or you already know everything about them (which is next to impossible), give yourself about 10 minutes of time and watch this video clip on Autoblog! Take the time to click on the "HQ" button and let the higher-quality picture load...it'll be worth it, I'm sure.