Parts - Anchor only one axis?

How would you go about anchoring one or two axes? I know how to anchor all of them but is there a way (Without a script checking) to keep an objects z and y axes the same but let the x move? I'm trying to reduce memory/processing power usage.

Thanks, If not I'll just use a script:

local origZ = script.Parent.Position.Z

local origY = script.Parent.Position.Y

script.Parent.Touched:Connect(function(touchedBy)
    script.Parent.Z = origZ
    script.Parent.Y = origY
end)