Looking at a used '06... Auto tranny question

[QC_GOAT]

When going from park to neutral, drive, reverse, there is a slight delay then prominent clunk from the rear end which causes the entire car to move up and down, forward and back slightly. I've had a similar experience with my ford explorer and the rear end needed to be rebuilt..twice. But is this normal for a vehicle with 400 torque or should I be concerned?

I've not had the chance to test drive it yet because they are waiting for the title to be transferred from FL.

The car is an 06 and has only 23k miles on it. Other concerns include the fact that it has all new floor mats, and the slightest amount of rust on the stainless looking door jam/running board panels, as well as a burnt out blinker light on the dash. Carfax and vehicle report provided by carmax are both clean. Do you guys think these things may indicate potential flood damage?

Verdict - I'm very skeptical about buying this car but I already paid $200 transfer fee and I'm convinced it's the only silver '06 I'll find with such low miles, so I'm just trying to support my decision, thanks guys!