On some of these there is no drain plug on the pan. I have an 81 300D parts car and there is no drain plug on the pan. Most of them do have it though.
To change the the fluid on these you can remove the drip tube banjo bolt, or just remove the pan. Just loosen the bolts and let the fluid spill out. Not that hard to do but get a wide pan or be ready to clean up a lot of red trans fluid.
There is always a drain plug on the torque convertor. It is not always easy to locate. Just pull that small cover from under the convertor and slowly rotate it with a screwdriver. Get a good light and you will sooner or later find it.
Good luck, and welcome to the forum.