Grinding/Whining & Transmission wont go into Drive
 

So I was sitting at a red light today, everything was dandy.. and when I started to accellerate the truck shuttered and almost felt like we got rear-ended. It was a violent shake. and then when i tried to accelerate it felt like it had slipped into Neutral. Drive is completely dead, when I switch to Drive, I get nothing. So I put it in 1st, and it worked, it went into gear. then when i started to accelerate it made this horrible scratching/grinding/whining sound. so i CAN accelerate SLOWLY and switch to 2nd, SLOWLY, and accelerate SLOWLY and switch to 3rd. 3rd feels good when I accelerate but then if i step on it, it slips out of 3rd back to that neutral feeling. If I try to accelerate quickly in 1st and 2nd i get that horrible sound and grinding feel.

you know what it sounds like, is if you were to pull a 100lb steel table along a concrete floor... very strange sound and feel. my GUESS was transfer box? Clutch? maybe someone else has the problem solved already?

The truck is a 2007 LTZ flex fuel 5.3L. 83,400 mi. No indicator lights, no nothing. just that horrible sound and feel, and Drive doesnt work.. I do have a powertrain warranty to 100,000 mi. so im hoping its considered a powertrain fix? its at a dealer now but they cant get to it til thursday, and i cant wait for an answer, and i know this is the best place for other chevy fans to give me peace of mind.



Any ideas greatly appreciated.

You just lost the trans. Did you buy an extended warranty? My '07 LTZ was up at 36K.

Power train is good for 100K miles and 5 years (I think).

yep, i was covered on an extended 100,000 mi. it turns out it was a Forward Sprag Gear, whatever that may be. I looked at a picture of it, looks extremely complicated. But if anyone else has those symptoms, its a sprag.

Same thing happened to me today at a stop light, '07 avalanche w/50k on it... glad that I have extended warranty on it, called my dealer, they said bring it in, warranty expires on 13th of May... phew...

(had so many issues with this truck)