i have an 02 camaro and my mechanic said the rear end is bad possible goin out..is this a bad thing?

Well deff. not a good thing your rear end is what makes the car go lol depending on whats going out depends on the cost of the repair but prolly be better off just replacing the hole rear end

replace the rear diff... i had lots of bearing problems on mine & should have installed a eaton posi. i miss the 35 th edition; fun car.

unless hes a specialist i wouldnt believe too much when it comes to rear end speculation. do a fluid change and put in some torco racing gear oil (rgo). that stuff works wonders. check the fluid you drained and look for "death swirl". if you have metal shavings pretty bad its time for a new differential but thats about the only way youre going to be able to tell without tearing it all apart.