Transmission "clunk" in 2006 XC90 V8
I have a 2006 XC90 with 118k miles on it. I purchased it recently, used, with over 100k miles. When I punch it the transmission down-shift makes a huge thunk, and it seems to be getting worse - either it down-shifts more or I'm noticing more of a think when it does. It has been pretty hot out here in Michigan, so that may or may not have anything to do with it.
So the first thing I'd normally do is check the ATF level, however apparently the '06 XC90, or at least mine with the V8, doesn't have a dipstick. The dealer says there isn't one and that the transmission has no regularly scheduled maintenance. Forum searches tell me that some people have very hidden dipsticks, and some people don't have any at all. I appear to be one of the ones that doesn't have one. I must, however, have some fill/check plug somewhere right?? Its tight in there, but I've checked the whole top of the trans the best I could and sure can't find anything.
Anyone know how I might go about checking the level on my trans? Once I can find that I can follow the change procedures I've found on this forum.
Or.. is this a normal thing to have happen in an XC90? This car overall is a lot less polished than what I'm used to, so maybe I'm overly sensitive (it IS a big thunk though, my 3 year old thought we hit something).
Thanks! Of course, I'm headed on a huge trip this weeked. Hope it'll be ok... I tend to be paranoid when I think something might be wrong.