The 6-engine Cordership is a c/12 diagonal spaceship that was discovered by Dean Hickerson on July 9, 1998. At the time of its discovery it was the Cordership that used the fewest known number of switch engines, though Corderships are now known that use as few as 2 engines.
There is another 6-engine Cordership that is quite a bit larger than the one shown to the right, with 265 cells. Its advantage is that it has a known glider synthesis involving 37 gliders and even has a gun that fires copies of it (see 6-engine Cordership gun).
A six-engine Cordership with known glider synthesisRLE: here
The 7-in-a-row Cordership from 1998 also has a 6-engine version, 6-in-a-row Cordership, though that was not noticed until 2010.