The term '4x4' generally means four wheel drive. It's based on the idea that the vehicle has four wheels and all four can provide power to drive the vehicle. What sets 4x4 systems apart from all wheel drive is that 4x4 systems are selectable; that is, you can choose whether to operate them in two wheel drive or four wheel drive. Generally the transmission is the same on 4x4 and regular two wheel drive systems. The power is split behind the transmission using a transfer case. The transfer case then sends power to two separate differentials: one in the back and one in the front. Of course, that doesn't mean there aren't some important differences between 4x4 transmissions and regular rear wheel drive transmissions. For one thing, capacity: a 4x4 transmission needs to be able to handle a lot more load than many two wheel drive transmissions. Another is that, because these transmissions have a transfer case built into the drivetrain, diagnosis can be a lot more complex. Very often the transfer case can mimic transmission problems, which can lead to unnecessary repairs if you don't know what to look for. That's why you should bring your 4x4 to your local Cottman center when you're having a drivetrain problem. Their technicians are very familiar with every 4x4 system on the road today. They know how to analyze their behavior, and they can isolate problems in the transmission and transfer case. So, when you bring your 4x4 to your local Cottman center, you can be sure you'll never pay for transmission repair unless you really need your transmission repaired. And that's a common situation, because most cars and trucks that come into a Cottman center with a 'transmission' problem don't actually need a transmission repair. That's okay, too, because your technicians at your nearby Cottman center are only too happy to get you back on the road... no matter what was causing the problem. So, if your 4x4 seems to be behaving badly, get it over to your nearby Cottman center. They'll do whatever's necessary to get you back on the road, fast!