I recently replaced my Aqua Magic V with a Style II. Here is a link to the
Thetford web site.
This link will take you to Thetford's list of different models. Click on a model and you will see the exploded view for that model and a parts list.
Removing your existing toilet is easy. Just like the toilet in your house it is held in place by two bolts/nuts on either side of the base. Once the nuts are removed lift the toilet straight up. You may want some short pieces of 2 X 4 to slide under the toilet so you can set it back down. Now you can turn the toilet to the side and remove the water supply. Before removing the water supply make sure there is no water pressure in your coach.
Your toilet is now removed. You can examine it to see what parts you might need.
For mine, I checked the price of the parts and the price of a new toilet. I also considered that all of the other parts on the toilet were the same age as the part that just failed. I also thought about the time to remove the old part and install the new part.
My decision was to buy a new toilet and replace my old toilet with a newer upgraded model.
Good luck and safe travels.
JD