I have a 1997 Manufactured Home. I want to remove everything from my bathroom and replace it with new. My question is: I want to remove the garden tub and put a cermaic shower in its place, remove the double sink and put a cermaic tub in its place, remove the toilet and put a vanity in its place, and put the toilet where the original shower was. Can I use the sewer drops and water lines that are already in place although I am moving the items around? And can and how do I relocate the sewer drop for the toilet.

You are going to move every fixture in your bathroom. It is kind of complicated to explain without knowing exactly configuration of your bathroom.

Post a sketch. We will comment on it and give you our suggestions. We will also draw new sewer/vent lines in the same drawing.

Question: is your house on raised foundation or on concrete slab ?

Back to you...

My house is set on a basement with 9 foot side walls and poured concrete basement walls. I want to remove the old tub, vanity, toilet and shower. I am going to lay down ceramic floor tile and put in a new shower, tub, toilet and vanity. But I am going to put the new shower where the old tub was, the new tub where the old vanity was, the new vanity where the old toilet was and the new toilet where the old shower was. I know that I have to move the sewer drop for the toilet, but I want to use the old drops for the others. I know I will have to cut some of the pipes and redirect them, but is there any thing else that I have to do? I don't know how to draw on this, but its something like this:

______________________________
]
Old tub old sink ]
]
]
] This is a wall like the others
] are.
]
Door o.toilet o.shower]
_///////________________________]

Sounds to me like you would be better off, with this layout change, to gut the bathroom, cut all the pipes out back away from the bathroom closer to the main, cut the vents off about 6' up and just start all over again, after laying new subfloor and framing the new walls

Follow the advice given by Chayn.
Many years ago I worked as a plumber in many of the mobile home factories in the area.
Here's a typical bath room drainage layout.