After a pair of 240z rear lower control arm spindle pin locking cotter pins. 55565-E4100
Probably no one has any as I don't think any other Datsun model uses these but the 510 guys might so worth a bash.
Cockram say $40 each and 6 weeks. Courtesy Nissan say $16 each plus $10 USPS.
If nothing here, shout out if you want some of these as may as well bring a few sets in.
Cheers and Merry Christmas

James