Rattling noise when going up a hill at a low speed

My 2007 ford fusion makes a horrible rattling noise only when its going up a hill that it must start at a low speed, where as pressing the gas when on the interstate while at 60 mph doesn't cause the noise. This car has a brand new transmission that was installed 13 months ago.

Has something wrong with suspension and don't know if this noise is connected with that or not.

Nice site :-)