I believe the 3.8L is considered the base engine and is intended to provide a lower entry price. It's a pushrod engine with two valves per cylinder, and is probably a lot less expensive than the 3.5L OHC engine with four valves per cylinder. Anyone in the market for a base Pacifica wouldn't be unhappy with the 3.8L compared to the 3.5L, though, since the driving experience, performance and gas mileage and would be virtually the same. I believe that all AWD versions get the 3.5L, though.
