I didn't like the way my auto trans was shifting so I had my local diesel shop install a new valve body. $395 for the part. $100 for labor. The difference is amazing for the price. Shifts are firm, no more hunting between gears, TC holds a little better too. I can't tell you why, but it works great. More power is definately getting to the tires. Even my girlfriend said it throws her into her seat more. For $500 bucks, everyone who has a stock auto and is modding their truck should get one. Oh, and it was another $130 bucks to fill 'er back up with fresh Amsoil and a new trans filter.