4t65 are all noted for blowing 4th except the 03 which had the hardened 4th hub. The 4t60 was limited in other areas but my 4th held up to being top swapped no problem in my 97 GP GT before going full retard 5 speed mod. On the plus side, those transmissions are out there and relatively cheap...on the negative side, it's probably not going to happen that you get your money back. How does the fluid level and condition look on the car? Any service history?