When I shift out of park, I heard a "plunk" sound from the passenger side. This happens about 75% of the time, especially when the car's been off for awhile. I thought it may be coming from the CV joint/axle but I see no tears in the boots and I can't feel any play when I wiggle it. This has been consistent for the last few months with no other symptoms. I think this sound is significantly different from the "thunk" of a bad motor mount, and seems to be coming from underneath. Any suggestions?