Ik3d

Hi Guys and Girls, I own a 1994 ST202 3SGE Auto Celica, long story short the gearbox or diff(?) decided to go crunch last week while I was driving along on the freeway. The car has 218,000 K's on the clock so is getting a bit old, the question I have is does anyone know what I'd be up for cost wise, and is the gearbox the same as the camry or RAV4 can it just be swapped in? Also what are the chances it did damage to the engine? I was doing 120km/h at the time.