I bought new faucet handles to replace the hot and cold handles on my tub. It's a 3-handle system with stems I can wrap my brain around - They're brass, they're threaded, they screw into the pipe. The problem is that Delta faucet's engineers are a bunch of expletives who designed these "faucet handles" to be more functional as paperweights or doorstops than anything else. I can't find a stem that's actually designed to fit these handles and delta won't sell me one. The hole the stem is supposed to fit into is rectangular with the set screw hole on the side at one of the corners of the rectangle. So, I think I've figured out a way to bastardize a plastic stem (like the danco 16219b) to make it fit the handle. What I can't figure out is how these plastic stems are supposed to attach to the plumbing. They're not threaded anywhere. Are there more parts that I'm supposed to attach between the stem and the pipe? If so, how, if the stem's not threaded? I've tried to see if it's part of delta's "Quick connect" system, but I can't find any kind of adapter that would thread onto the pipe either. Before I go any further, waste any more money, or give myself an aneurism, please, someone explain to me how these plastic stems are supposed to work. I thank you.

I am not sure I fully understand your terminology. The hole the stem fits into is always round, not square, that's at least in my region. It would be very helpful if you snap a picture of the stem, the faucet and the handle - and post it to better describe your dilemma.

In the interim: Stems and Handles are not interchangeable. There is a high probability you will be able to install same brand handles on same brand stems - but different model . However, stems of one brand will most likely not accept handles of another brand.

There are few companies that make universal handles, meaning, the handles will fit several different faucet brands regardless of its manufacturer. These handles usually come with plastic adapter. Adapter will fit onto the stem and handle attaches onto this plastic adapter. Adapter and Handle are held in by set screws. Note: here, you have to purchase Handles with Adapters included in the same package.

However, retrofit is not very professional way of dealing with situation like yours. You will be better off if you purchase new handles - not a retrofit - to fit your stems. These handles attach directly onto the metal stem with brass or s.s. screw. They will feel solid and will last significantly longer than cheap, retrofit handles.

In this case, you have to know the brand name of your faucet. With this information in hand, go to your local Plumbing Supply Store and they will tell you what kind / type of handles will fit your stems. If it is one of the major US manufacturers, like Delta, American Standard, Price Pfister or Moen, you can probably buy new handes in Home Depot or Lowe's. Otherwise, don't waste your time and go directly to a professional supplier.

I agree that those hole are usually round, but here's what delta did:
http://i45.photobucket.com/albums/f6...k/P1010007.jpg
http://i45.photobucket.com/albums/f6...k/P1010008.jpg

This is what I want to replace:
http://i45.photobucket.com/albums/f6...k/P1010006.jpg

I have no idea what brand is going on behind the wall, but it looks sort of like this:
http://i45.photobucket.com/albums/f6...ase_media2.jpg
Pretty standard, right? And not being a plumber, even I can see how it works.

What I would have to replace it with to make these handles fit looks something like this:
http://i45.photobucket.com/albums/f6...base_media.jpg

How in the world that is supposed to be secured to the pipe is what I can't for the life of me figure out.

The "brand" of everything else I've replaced so far, from doorknobs to faucets to light fixtures is what I refer to as "Contractor Special." The tub faucet looks about the same. Since we bought the house as an REA foreclosure, I don't even know when the plumbing was redone, let alone by who or with what, and no real way of finding out. It was built in the early 1940's and I'm an Art Deco nut, so having this cheap-looking (and sticky grimy) faucet defiling my bathroom makes me angry. I also want to update it in the style that's true to its era, so I don't want to settle for just anything because it happens to fit. I know it may seem weird, this quest of mine to get these handles on. Most people would send them back. But my house and I are very picky. I also don't want to be defeated by corporate proprietarianism. I want to thumb my nose at delta because I know they only designed it that way out of greed.

Stop! You are going completely wrong direction. The stem will give you the type of handles you can install. Forget the Pearless / Delta white plastic stem you posted photo of. You are trying to fit engine from Bulldozer into Corvette. It won't go. No way around it.

The faucet you have is regular Price Pfister. They offer wide range of handles.

If you really want to use those handles - then cut open the wall, remove the rough-in body valve, replace it with new one of your choice and with the one that will accept the handles of your choice - and patch the wall.

BTW: the white plastic stem you've posted photo of is NOT from tub/shower faucet - but from sink faucet.

I forgot to say also that I did go to Home Depot first to get the stems, because they sell the handles. They told me they don't sell the stems, not even as a special order. They told me to contact Delta, which I did, and Delta also told me that I could not order the stems, most likely because I didn't start by ordering the $300 full shower system that I would have to gut my bathroom to install - at least that's what they hinted at.

Thanks. I couldn't find a picture of the tub/shower equivalent, and I haven't bought anything else because I was afraid I was going to get the answer you just gave me- that I would have to take the wall out to make it work. But, seeing as how I can't get the part that I would need to rough in, not even from delta, I suppose it is time to give up and sell these paperweights on eBay.