I think early US cars got Girling rear calipers as that axle snubber didn’t come in until the early 80s? So you can get Girling caliper pins cheap from RockAuto...for example:
https://www.rockauto.com/en/catalog/volvo,1977,244,2.1l+l4,1287334,brake+&+wheel+hub,caliper+slide+pin,10281
Of course it’s not a high-dollar item if you can get them for 3x the price locally then that’s the way to go because they’ll only be like $5 instead of $1.60 LOL!