Not exactly sure what you are asking, but here are your options:

1) (easiest) replace the parts using Moen parts. One exception is the tub spout, which can be replaced with another brand/style, etc, but first you need to know how it's connected and get something similar (slip-on with a nut underneath, or screw-on). Usually this is done by removing the existing one and matching the connection type. Tub spouts are attached in more than one way (slip-fit over copper, and a couple different screw-on variations).

2) (more costly) Replace the entire unit, guts and all, which typically means access behind the wall, sweating copper, etc. This is where you make sure to get something with the exact same configuration for all the existing holes, which can be a nuisance.

Also, Moen guarantees for life, so you can call them and get a free cartridge if it's leaking, etc. As for the handles and trim plate, they usually clean up fairly well, but if you need to replace them, look for a "trim kit" or trim plate and be sure that the screw holes in the trim plate are in the same place as the one you are replacing. The trim kits bought at a plumbing supply have the screw holes in a different location from the trim plate you find at Home Depot, etc.

Same goes for the handles, meaning that you need to take one off and take it with you to match the backside of the handle "stops" because they can differ.

Good luck.

After rereading your initial post, I would suggest calling Moen customer service. With an adequate description of what you have, I think they will be able to figure out the necessary parts and send them, free of charge.

Here is a link that might be useful: Moen Customer Support

A 35 year old bathroom is ready for much more than a faucet repair. Time is running out on replacing the whole thing. You have every chance of coming home to a much bigger problem soon. Don't waste your monry on a stopgap. You'll need it for when you open up the walls and do the whole thing right.

Thanks to both of you. I'm sorry I wasn't clear to what replacements I needed.

The initial problem was, the hot & cold knobs had to turns several times before water would begin to run. I had someone checked out and it seemed the cartridge and handle stem need to be replaced. Was going to replace with different type of hot/diverter/cold handles for easy use. That was why I was wondering if the 3-handle piple unit inside the wall was of standard size.

Since Moen has a lifetime waranty and it may not cost me anything but maybe labor cost, I will start with this approach first. I will give them a call. Thanks.

I don't want to get into replacing the whole system if I don't need it yet. It will mean to replace part of the wall, tiles, etc.. Sort of like opening a can of worm. If I had the money, that would be no problem but I'm living on a disability income. Got to watch every penny spent.