Help.....Im super sorry I did a quick search but im really short on time and the mechanic locked my family out of the yard.

Does changing the rear diff gears affect the transmissions ability to shift if they have been changed. My family went into the shop with a minor vibration problem and a perfect shifting car. The guys changed everything from the trans back , coupling, ujoints, pinion gear, ring gear, axles......for a minor/occasional vibration. Now on the test drive the car wont shift, wont go into reverse, wont go over 30mph.....help!!!!!

 

Of course im an idiot its a 99' V6 auto.

 

Those things should not affect how the trans should shift. If he rebuilt or replaced the trans, sometimes it takes an auto a few miles to break in and start to shift right. All the autos ive had rebuilt would slip, or seem like they didnt want to shift right for the first few miles. That being said, it sounds like yours isnt getting out of first gear, the rear gears should have nothing to do with this. I would look under the hood and under the car and look to see if he might have left a cable or something else off.