cool. so what usually happens to make an axle go 'bad?' do they just fracture? the splines wear down on them?

also do you know anything bout that popping noise when i take off? thats what's buggin me the most. i guess it could be the suspension adjusting because of movement but the car has aftermarket coilovers on it and good shocks so that wouldnt make too much sense. what do you think?

and sorry if these are dumb questions. i dont know jack about FWDs lol