I will write this here because I realized in my research, that this particular stem was not very common .. or at least, not common enough that people are writing about it in question/answer forums. It was very hard to find information, so I hope as this post becomes immortalized on the internet, that people might find it again in the future.

My story:

My shower head was dripping, and that lead me to see the reason as the hot water handle. I watched many YT videos, and they all mentioned a screw and a washer, and possibly a seat, that would need to be replaced. I felt confident to do that much.

But it turns out, my particular bath handle is a Pfister with a different kind of stem/cartridge. It turns out that I needed one that could be replaced with an item called

"Danco 9H-8H/C" (this item is currently easy to find on many websites and local stores, even if they don't carry as many of them for some reason). I went to my local Lowes and found only 2 .. I went to my local Home Depot and found none at the store, even no empty spot where they might be (though it is showing up on both stores' websites). Compare that to many other kinds of stems at the same time, still many were hanging on each peg.

Example of the item:

https://www.homedepot.com/p/DANCO-9H-8-Hot-Cold-Stem-for-Price-Pfister-Faucets-05850B/100571452

The original Pfister part is "Pfister 910-030 OEM Valve stem".

If you just need to replace the washer, then that is possible. I'll get to why you might want to try this.

https://www.amazon.com/Danco-89045-Bottom-Seal-Washers-Pfister/dp/B001ULAL70/

If you are the original owner, you may also be able to get a free replacement part. Check the Pfister website for warranty information.

https://www.pfisterfaucets.com/parts-support/warranty-information

In my case, it seems like the washer at the end, had become stuck to the pipes behind the wall. When I pulled out the stem, the washer stayed inside, and the stem itself came out, without that washer. It really was stuck because even if I moved my finger on it, it did not come lose from the wall of the pipe.

I thought it strange but not knowing about pipes, I also did not want to dig at the washer with a plier or pulling object. What if I created more problems by now having a washer that was all torn up, but unable to be removed fully from the pipe, creating contact problems for a new washer?

In the end, I went and got the Danco stem product mentioned above. I took out the new washer from the new one..and stuck the new stem into the pipe, hoping to make a connection with the washer.

Somehow, that seemed to do the trick, because after putting everything back together, there was no more leak.

I also admit that maybe the old washer was still OK, but something on the old stem was not holding out water. I can't confirm that though, since I could not get a good look at the old washer or I did not know how a new stem will hold off water since this stems seems to have holes in some of the white non-metal parts.

I don't suggest this method though. You should want to use the new washer with the new stem. Maybe your old washer will come out with your old stem. However, for now, it made me feel good that there is no leak, and if a leak develops again in the future, I have more knowledge about how to go about fixing it.

Now as for why you may just want to replace the washer only . First, it's cheaper. Just a washer compared to the whole new stem. Secondly, based on reviews, there seem to be some problems with this Danco stem. It seems to break again much sooner than later (check various sites for those reviews, so you can see it from the perspective of the person experiencing it). So a trend in the reviews seem to say that there could be design flaws in the Danco item, and if your original Pfister stem still works, then maybe just replacing the washer will be viable.