My '03 Chev 2500HD with an Allison trans has 38,000 miles.

I know these trannys whine a bit but mine is getting louder with time. Is this normal????

Reason I ask is that my dealer recently took the trans out to get access to the oil pan on my duramax and whn I picked it up it had a new oil pan on the tranny. They said it slid off the tranny jack in the shop. Is it possible that there was some internal damage to the tranny when they damaged the oil pan? Seemed the whine was more noticable as soon as I picked up the truck after the work was done.

The dealer says the damage was superficial to the pan but how would I know. Maybe I should ask them to take the pan off and have another look.

Is there anything internal that could be damaged when they damaged the pan???