Mobile Suit Gundam Thunderbolt is set during the same time as the original 1979 anime, but is set in a different theater of war, which is in the Thunderbolt sector.
It is based on the Gundam spin-off manga by Yasuo Ohtagaki, and was released in four parts.
The first episode was also streamed for free last year, however, no word on whether the third and fourth episodes will also be getting the free YouTube treatment.