looking for owners of 2004-2005 Pace Arrows

Okay, I've resisted asking this question for fear of sounding stupid, but I just gotta know. I'm pretty sure of most of the sounds my engine makes, particularly when pulling hills, or running in warm weather. But the one sound I can't figure out is the ratcheting sound that seems to accompany shifting. It's not particularly loud. I'm sure one of you can enlighten me.

Thanks