At about 3,000 miles (1st oil change) I noticed a metallic ticking noise that seems to be coming from the area around the oil filter. I took it into the dealer and he said that it was coming from the Allison transmission and that it was normal. I think that he said it was the "rhythmic ticking" of the transmission. I bought two identical 2005 GMC 2500HD D/A's at the same time and the other one has about the same miles on it and does not make the noise. Has anybody had the same problem? Also, does the Allison come from the factory with synthetic fluid or Dex III type?

the "tick" is coming from the engine and considered normal. something about air bubbles or something in the oil. If you do a search on "tick" you'll probably find lots of info. I also think there may be a post about it in the TSB section.

I think this may answer your question ...

http://dieselplace.com/forum/showthread.php?t=142&highlight=engine+tick

Mine does it, mainly on warm-up. Once its warm, it seems to go away.

It comes with synthetic from the factory.

Negative on the synthetic oil. All of the pickups come from the factory filled with Dexron III.:ro)

It comes with synthetic from the factory.
I was unaware of this. Which synthetic to they come with?

I have a friend who has a transmission shop, he pays for technical information provided by Transgo. Transgo says that the factory fluid is really good stuff, and not to change it unless it is burned or really high mileage. I don't know who makes it.

Thanks to TopHog for the link. That sounds exactly like the problem.