My period for loving tokusatsu programs such as "Ultraman" （ウルトラマン）and "Kamen Rider"（仮面ライダー）was as a pre-pubescent kid in the early 1970s. By the time the 1980s rolled around, my interest had long turned toward anime, especially those series done in the Leiji Matsumoto style, so as such I'd never heard of this program "Uchuu Keiji Gyaban" (Space Sheriff Gavan) in its first run. Reading up on the Wikipedia article, I was surprised to find out that this particular tokusatsu had partially inspired the powers-that-be to create "Robocop". And by the way, the English translation of the title strikes me as being pretty cool...I think "Gavan" would be an excellent name for a sheriff cleaning up a dirty one-horse town. Just imagine:
"Ma'am, my name is Gavan...Sheriff John Gavan!"
The opening theme, "Uchuu Keiji Gyaban", though, sounded like something that I had heard before so I'm assuming that the song has frequently appeared on retrospective shows. And listening to it again, I definitely got this disco-era Rod Stewart vibe from the pumping heroic melody by Michiaki Watanabe（渡辺宙明）. Keisuke Yamakawa（山川啓介）provided the lyrics and the prolific Koji Makaino（馬飼野康二）helped to arrange the song. I think the kids at the time would have been pretty psyched to see the opening credits with the theme playing. Frankly, given a decade, they could have been dancing to it in the nightclubs.
But the fellow growling out his manly vocals was not anison master Isao Sasaki（ささきいさお）but Akira Kushida（串田アキラ）who has specialized in theme tunes for both anime and tokusatsu. You can check out his Wikipedia page here.