I got my MK X at Sol station (mark of exploration vendors). Where is the ship equipment vendor at Gamma whatsis?
Gamma Orionis. You have to fly to Battle Group Omega and then come close to the U.S.S. Montgomery Scott, located to the left of the lead ship U.S.S. Victory.
The Montgomery Scott offers purple Mark X equipment, mostly Antiproton based, in exchange for new marks that you can get by running a "daily" repeatable quest.
By the way, you have to be at least Rear Admiral 3 to be able to get a mission which allows you to enter the region.