They do wear but I’ve never seen or heard of one wearing out altogether. I had a 9s from 69 which I know had it’s original stem (no p) & the gap had worn down considerably. Who knows why the gap differs on many estates? Difference in vulcanite quality, home sanding or doctoring, expansion in the shank over time? Only thing we know is that they never wear out completely, which is all we can ask for really.I agree 1976 and yes some original stems dont have the script P
I too have a deluxe that has the space missing,in my case you can see where it has had the taper on the stem filed down Badly
i know it is said the space is to allow wear but I personally cant see the join ever wearing that much .
Even on 100 year old pipes the space isnt closed much if at all