Re: can someone please tell me what goes here? picture inside
Bottom port is the exhaust, and it appears one of the shutter or flapper valves have come loose from further up in the exhaust, so you will need to look into replacing them, and removing the loose shutter.
U-joints appear to have been bathed in water, and are probably shot along with the bellows, and gimbal bearing. Just out of curiosity, have you drained the oil out of the drive yet? Some of the drives out there have little tolerance for water intrusion in the bellows area, and the seal that seals off the yolk on the drive will allow water in.