Earth is under attack! The evil cyborgs known as Meganoids are out to convert mankind into machines, using spaceships, anti-gravity devices and other nefarious means to achieve their goal. But while the Meganoids have plenty of firepower, they’re no match for the young Haran Banjo and his transforming robot Daitarn 3! With speed and panache, Haran takes down fiend after fiend with ease. Alongside the lovely Beauty and other fighters of justice, Haran and Daitarn 3 will save humanity and take down the evil invaders!
Kappei is your normal run of the mill delinquent lad, riding motorcycles and trying to gain leadership of a gang. When fighting with a rival, they are both attacked by a strange creature! Fleeing to his Grandfather's nearby sea rig, Kappei is knocked into the water and is rescued by a giant spaceship piloted by his grandparents. Before he can figure out what is going on, he finds himself in the mighty Zam-bird, fighting against the monster that attacked him - a mecha-boost of the planet-destroying Gaizok! Kappei isn't the only one in his family who ends up with a giant robot, though; his cousin Uchuta pilots the Zambull and Keiko pilots the Zambase. Together, the three of them can transform into the Invincible Superman Zambot 3!
The similarities between Zanbot 3 and Daitarn 3 are pretty obvious:
All kidding aside, both series are typical examples of the late 70s mecha shows. If you enjoyed one of them, you are more than likely to enjoy the other.