It has linear rail looking blocks, but they don't look like standard type linear rails, a mate reckons they must have needle rollers inside as they are too small to be slideways, might try doing some investigating on that. The X is the only one I've cleaned up for now and it moves quite easily turning the ballscrew by hand.
The X Ballscrew is almost perfect the entire length, only one end has some slight rust pitting on it, will have to spend some time on that.