C180 Gearbox - Tech Question

[Troybluec180]

My 94 c180Auto has 66000 miles done and I notice a vibration accelerating through 30 mph...any ideas.
Also is there a timing belt on this car that need replacing??
Excuse my Ignorance ..I'm not very mechanically minded

 

[piestore]

gearbox

What makes you think vibration is gearbox?????

No timing belt all done with chain and there is no specified time to replace this.