GMC Repair: GMC Envoy, blump, gmc envoy

Question
I have a 2002 GMC Envoy that has been a great car for the most part.  Last month, as I was parking the car, I heard an unusual "blump" sound but thought that it was from turning too sharply.  When I returned to the car, the lights would come on, power doors worked, radio, etc but the car wouldn't start. I had it jumped but even after driving it to charge the battery, the battery would not stay charged so I took it in and the mechanic said that it was in fact the battery.  (The battery was ONLY 6 months old and I had not left anything on, i.e. lights, door open, etc.  TODAY I made a left hand turn into a neighborhood and heard a terrible noise, a loud blump under the car; I thought something had fallen out from under my car. I got out and inspected underneath... nothing was there, not even a screw.  Then when I drove away it made a grinding noise which grew louder as the speed increased from zero to 5mph. I pulled into the driveway and now the car won't back up. The stick moves into gear but the car won't. HELP!!!

Answer
Hi
It sounds like the reaction sun shell inside the transmission has failed.
It is a fairly common problem.
I do hate to say, though it is an expensive repair.
It can run as high as $2000.00, depending on where you have it repaired and the cost of labor in your area.
I hope this helps
Good Luck
Pawl