Finding Gottlieb connectors is difficult but as posted by the previous person they can be reused unless they're physically falling apart, burned, etc. I repinned almost everything on my Mars and it took me a long time to find a system that worked. The pins can be a bitch to remove; I had way too many that I spent 10 mins prying/yanking little pieces out because it broke.

I unplug the connector and lay it with the back side facing up. I push downward with a pocket flat blade screwdriver with moderate pressure to depress the catch/tongue. I wedge the pocket screwdriver in the top end of that same little slit and push the pin backward. Once it's about halfway removed I gently pull it the rest of the way out by gripping the wire in one hand, the connector in the other and pulling. Sometimes the pin will break off inside or the wire will tear away from the pin but it is still removable.

Pins for interconnect harness and A3J3: https://www.arcadepartsandrepair.com/store/pinball-kits-parts/pinball-parts/bifurcated-edge-connector-split-pins-18-24-awg-100-pack-me1004/ (100 pack)
https://www.arcadepartsandrepair.com/store/pinball-kits-parts/pinball-parts/bifurcated-edge-connector-split-pins-18-24-awg-10-pack-me1004/ (10 pack)

Pins for other weird style Gottlieb edge connectors like A3J4 can be found at PBR: http://www.pbresource.com/molex.html (part# GTB-0850-0105)

Pins for power supply are standard trifurcon 0.156" that can be found anywhere.

I found that when I reused the original wiring in repinning the interconnect harness, the harness ended up becoming too short to reach between the two boards. I think I will have to drill new holes to mount the posts lower.