Caliper ID ?????? Help

I'm rebuilding my 1973 Dart Swinger & want to rebuild my caliper's. According to the book I have a sliding caliper but that will not help when ordering parts in the US.
What sort of caliper have I got?
How big will the piston be & is there a rebuild kit for them?

I can order new calipers from Rock Auto but the freight is on the high side so a kit will be the best option.

Can anyone help