when driving makes grinding noise

when driving on 3rd gear mostly or 4th i hear i hear a grinding and rattlin not 2 loud but like a buzzin type sound coming out of the passenger side… only when u accelearting it makes that noise… if i put it on nutral it don’t make that noise and if i turn it don’t make it when on nutral while car moving… but when i put gas again it makes that humming rattly grindy low noise… what can it be??? please don’t say somthin really big and nasty… thx