mohammed

Hi all. im new to this forum and its my first post. i have the e90 330d. no mods. full service history and transmission fluid changed at 85k. mileage is now 115k. just got one small issue. under slightly more than moderate acceleration i get a thump/thud at around 3 thousand revs. for example: im doing around 40-50mph, i go to speed up, it downshifts perfect, i hit around just over 3k revs, then i get a thump/thud from the rear, then it over revs a bit as my foot is still on the gas, then my traction light flashes. all this happens in a matter of 2/3 seconds. any ideas what the issue is? i get no vibrations, no clunks, gears change smooth, no leaks, new diff seals a year ago. all mounts and bushes are in good condition. will it need a transmission software update. please help. thank you