GMC Repair: Strange Noise, shell gear, low pitch

Question
QUESTION: I had an oil change a couple of weeks ago, on my 2005 Yukon SLT @ 86,000 miles.  Since then when I put the trunk in reverse and sometimes going forward I hear a strange sound.  It's sounds like something is going on with the gears, the ride is the same and exceleration is no problem.  I noticed the guy changing my oil attempting to start the truck in neutual, then he put the truck in park and it would not start, he then needed to jump the truck to get it to start.  I have never experience this problem until that oil change a couple of week prior. Did this guy cause this problem?

K

ANSWER: Hi
First I re set my vacation dates as i have just recently lost my brother, and have been busy with the estate dealings. So you'll need to email me a responce.
Please describe the noise in more detail.....is is a klunk, one time only when gear selected, or is it a whirring noise, grinding (like metal to metal), high pitch, low pitch..etc...
I am not going to totally speculate on the repair shop causing problem, but I will say in MOST likelyhood, it will have just been a coincedence.
You can reach me at
mtek77@netscape.net
Thanks and sorry for the vacation foul date

---------- FOLLOW-UP ----------

QUESTION: Hello,

Sorry about your loss.  The it sounds like a whirring/grinding low pitch upon breaking or putting car in gear; however it does not happen every time.

K

Answer
Hi
My dates messed up!
It sounds like it is probabally the Sun reaction shell gear, inside the transmission.
I would advice you to take it to a tranny shop in your area, and have them listen to it.
It is a fairly common problem, and it is a fairly expensive repair.
It will lead to total transmission failure at worst, and loss of reverse at best.
I am sorry, of course, remember, this is just a guess from experience, not a total diagnosis.
Most shops will at least listen and give an estimate for free.
Thjanks
Pawl