Ok, so when i drive in rain and go above 40mph theres a humming sound underneath the car not sure its the transmission. If i slow down it stops. This only happens when it rains. any other time its all good. Any recommendations.

 

This might be the same as your issue.
https://volvoforums.com/forum/showth...ght=S60R+noise
https://volvoforums.com/forum/showth...t=26156#141278

 

Rain squeal is usually a loud high pitch noise. But if it is the rain squeal it's the center resonator expanding upwards and rubbing against the drive shaft. You can actually see a scorch mark on your drive shaft where the contact occurs. The easiest and cheapest thing to do is to cut out your resonator and replace it with a straight pipe. Any exhaust shop can do it for anywhere from $40-$80. That's what I, as well as tons of other guys have done on SS to solve this problem.