I used the Dupont female connector. I was leaning towards buying E-Z Hook HKM series grabbers, made in USA. They use a 0.025 inch square pin.
Ended up buying used HP grabbers off e-bay, they also use the C cross section. The combination seems to work but I have had some flaky connections. The orientation of the of the receptacle onto the pin does seem to have a preference.
The original round female connectors could be from Amphenol/TRW mil spec connectors.