get a big screwdriver and a hammer and try and tighten the diff
the noise you are hearing is coming from the shafts as the bearings are loose in the diff
most vxhall gearboxes u can detatch the diff with only a few bolts and taking out the shafts before the diff, saves replacing the whole box
i had same problem on my cally ecotec with banging on acceleration and braking, i found out it was the shafts but after repalcing with other shafts it was stil ldoing it, i noticed the noise by giving the shafts a good tugging 😛 and found the noise was coming from the diff, so i tried tightening up the diff by using a screwdriver on the the little ridges and bingo it worked 🙂