Odd faucet stem help

My house was built in the 60's and I assume original 3 handle bathtub faucet. "Standard" "Made in USA" is stamped on the drain lever cover. I can remove the handles and escutcheon and the packing nut with a 5/8" wrench. I see a larger hex nut behind that. The packing nut was screwed into that larger hex. However that larger nut is rexessed about 1/4" in a thick sleeve. The points of the hex are flush tight with the sleve ID. A flat blade screwdriver will enter between the hex flats and sleeve ID. The sleeve is too far into the wall to grab on the OD. I can see all the way back on the sleeve OD and there is no hex feature for a socket. I tried backing the stem out throught the packing with no luck. Do they make a socket with tabs or ears to engage the hex flats inside the sleeve. Or is there another solution.
Thanks for any help.

If it is an American Standard brand, then all three styles from that era have a spot to put a wrench on to remove the entire stem. As would Price Pfister. However, without a picture, or something to look at, all we can do is speculate.

A picture would help, but in almost ALL cases, the sleeve unscrews first. "Standard" on the drain cover has absolutely NOTHING to do with the brand of the faucet.

Photo attached

Attachment 18186

Any takers now that a photo is attached. The packing nut is removed in the photo.