It is titled Mazinger Z in the cartoon. That's just a hard habit for me to break, since I first saw it as Mazinga and that's what I've always written. This is from the original English dub. Apparently there were 27 episodes dubbed into English back in the day. I've got a compilation movie of the first four episodes. The dubbing isn't bad, but it's not great. Too bad Titra didn't get to do it.
I wonder why they didn't do the entire series. 27 episodes isn't even a third of all of them. It's a fairly violent cartoon, so perhaps that's why it wasn't finished.