this is PD-M324 with two O rings in place of each original seal. Fitted in seconds, costs pennies, works jolly well.
[edit; the O rings I used were 12.7mm ID, 17.5mm OD, ~2.4mm cross section, i.e. 1/2" bore, 3/32" section]
The same scheme works on PD-M535, PD-M505, etc.
If you need the tool TL-PD33 this can usually be found for about £30 (sometimes a lot less than this) if you shop around. For example by spending fifteen seconds searching I found it for £32-something on amazon with free delivery. I doubt that it is the cheapest price you can get it for.
BTW PD-M535 is not a good spare part donor for PD-M520; I don't think they share any parts.
PD-M535 EV techdoc
https://si.shimano.com/pdfs/ev/EV-PD-M535-1520B.pdfIf you don't fancy O rings the genuine seal is the same part as fits PD-M324, PD-M323, PD-M505, PD-M730 etc and is available here
https://www.sjscycles.co.uk/pedals-cleats/shimano-pdm324-axle-seal-y41612000/BTW the part is not correct for PD-M515, despite what it says in the link above.
**Brucey top tip** when searching for a nine-digit shimano part number, it often pays to try different things like
a) punctuate it differently (e.g. with/without gaps, spaces, dashes etc) and/or
b) delete the first and last digits so that you search for a seven digit number instead
on the latter point shimano 416-1200 is equivalent to shimano Y-416-12000.
cheers
