GMC Envoy Transmission Issues

Kinda hard to guess at this without seeing the vehicle If there is a grease fitting on the drive shaft slip yoke, then grease it. Else pull it out and pack it with a good grease. That's the cheapest easiest thing to try. Sometimes that can cause the problem you're describing but that's typically when you start and or stop moving in the vehicle, not just when it's put in gear. Everything else I can think of requires me to actually see the car and experience the issue. Is there anything else you can tell us about the problem.

It all started with the dealer doing an oil change (we were having no issued with the vehicle)and deciding that a seal in the transmission needed replacing. They "fixed" it and the morning after we got it back the transmission died alongside the road. You could start the engine, but it only "clicked" when you tried to put it in gear (either forward or reverse). They said it was an easy fix, they would just need to make a small adjustment, but now it's been three days and it's not fixed yet and they are replacing the torque converter. They don't seem to know when this will be finished. And I don't think they even know if this is the problem, though they assure us it is.

can anybody tell me why a 2005 GMC Envoy transmission is not compatible with a 2004 envoy

what grade of oil did they use? If your envoy is a denali it takes only 5w30. any thicker and the oil will not pass through the mesh filters in the engine. This happened to our envoy denali twice, we ended up replacing the lifters...twice. about 2 weeks after the oil change The truck jerked violently when i put into gear and park, also when the lifters broke it started to shift violently when switching gears on the road. I have my dad change the oil now or buy my own oil and take it to the shop.