iceman89gt

having a problem with the tunnel cracking all the way up past the front of drive shaft on my 89 gt from leaving the line so hard and also from the guy i purchased the car from not installing the upper control arms on the rearend correctly. he welded them to the frame on one side and to the tunnel on the other,thus causing cracking. i dont know much about the fab work but i was told that to put in new floor pans, reinforce with plate , draft shaft loop, chassis, and new control arms, and all this without destroying my interior or backseat would cost anywhere from $4000 to $5000. is this reasonable or can it be fixed with less for less???