I replied to your PM. You need to find out what transmission you have. I'm not sure if the 3400 came with a 4t45e or a 4t65e. If you have a 4t65e then you can use it. You're going to need that list of parts to run the 3800 period. Just get the front clip of a wrecked 3800 2nd Gen Wbody and swap everything over.