Quesh shares all three datacrons with both factions. It also is completely open to both factions, so be careful about Open World PVP and getting ganked.
Republic Mining Camp
(Deep in Empire Territory) Travel to the Tainted Valley and look for two large venom pipes running from the wall into the ground. From the pipes, hop up to a ledge against the wall on the right. Walk around the large fenced in area until reaching a piece that has been removed. Once inside it is a piece of cake to find the datacron, which is out in the open.
From the entrance to the Yuna Crosscut simply follow the tunnel to the center. The room in the center of the map has two switches on opposite pillars and a switch outside the room. Activate the switch outside the room from inside (manuever the camera until you can see it) and it will begin filling with a deadly gas. Quickly rush to the switches on the pillars and activate them both. If done fast enough the gas will shut off and the force field over the southern exit will turn off. Quickly head through the southern exit (or the force field will reactivate) and claim the datacron.
Three Families War Camp
(Deep in Republic Territory) Pass through the security forces guarding the Hutts’ palace at the Imperial Garrison to the right-hand side up the hill until it ends at the corner of the wall. There will be a very narrow ledge that wraps around with the wall for a few meters before widening. Keep going past more walls to another hill. At the top of the hill is the datacron.