2002 suburban 4x2 105000 mi...just had 90K mile factory recommended service/PM,(all fluids done). Engaging transmission into D or R from Park is a hard or rough engagement. once driving, shifts up thru the gears nice and smooth. When first speeding up or when slowing back down, under 25 mph, clicking noise is heard and felt from the rear end. Also, at 65mph and above there is a substantial vibration. I have had the Michelin tires rotated and balanced, dont know if all of this is realated. Any ideas before I take it in and someone wants to sell me a new transmission? Is this tranny, rear diff, any other driveline issue?