Put transmission into drive makes a hard sound

The gurgling sound is most likely air in the cooling system moving around in the heater core when the engine shuts off. Check the cooling system for the proper coolant level. You may need to purge air from the system depending on which engine you have.

Could you take a video or record the sound and load it on this site? Sounds are very difficult to diagnose without hearing them as they happen. It could be the transmission or something like a bad engine mount allowing the engine or attached part to shift and hit on the sub-frame or body.