Q: why wont my `06 chevy tahoe shift into drive and go but when in park and shifted to reverse it will reverse?

Hi there. A car that refuses to shift or go into gear easily is trying to tell you something is wrong and in most cases the culprit is the clutch (in a manual transmission) or torque converter (in automatic transmission). Transmissions are very complicated and have many moving parts, ignoring a hard to shift issue can quickly spiral into a very expensive transmission repair. Over time, especially as a vehicle goes over the 100,000 mile mark, parts and gears inside the transmission simply wear out. This process can be dramatically accelerated if the car is driven with low levels of transmission fluid. The transmission will have to be rebuilt or replaced which is a very expensive repair. Symptoms of a failing transmission include hard shifting, humming, clunking or grinding. It might be best to have one of our professional mobile mechanics come to your location and complete a car is hard to shift inspection, so they can determine the best course of action.