The centre pivot of the swinging arm and the centre of the output shaft on the final drive (bevel box) share the same centre. When your driving normally the top of the belt is in tension being pulled by the bevelbox drive pulley. Under very light load if you go over the bump the swinging uarm comes up and has the effect of unloading the belt which causes a backlash noise from the BB. It's the same noise you get at very light throttle and you go from drive to over run and back to drive. If this is the noise it's completely normal and you get used to ignoring / driving with it.
If it's not this, when is the noise at it's worst and when is it gone. This will give us a clue. The modern cars are generally pretty robust - you won't have damaged anything I'm sure. You will get used to these noises - generally if it's still going it's not broken. The noises and rattles will probably change and come and go every time you drive it, it's the wood / aluminium / steel chassis and a big lumpy engine all creaking away - bit like a big sailing ship - you just get used to it. Just enjoy
