Awesome thanks Chad - different designs but the same purpose.
Who would have guessed they were referred to as monkey nuts! I’ve now searched for dropout spacers (instead of insert) and found lots of options.
In case anyone is curious I am doing a sort of resto-mod Peugeot build. It already feels like the little bits to make this bike work well are going to cost way more than the bike did.
Some things had to be changed like the really short seat post, other things are being changed just because I have the parts (alloy wheels with an 8 speed cassette for example - which required cold setting the rear dropouts to 130mm)
I am genuinely not sure how far I’ll take this. I would prefer to keep the original paintwork but at some point paint would totally refresh the bike.