Space Runaway Ideon (1980)

Space Runaway Ideon begins in 2300, far enough in the future that mankind has begun colonizing other planets. On the planet Solo in the Andromeda Galaxy, a group of archaeologists had come across the mysterious remains of the Ideon—three large armored trucks with the ability to transform into a godlike mecha. They also come across a large spaceship, known as the Solo Ship. For six months they had diligently restored the machines but failed to get the giant tanks to move. Suddenly, a humanoid alien civilization known as the Buff Clan comes across Solo. A long death ritual begins.