Join Date: Nov 2002
Location: Boston Mass. area
Rep Power: 0
Almost certainly it should be held down. Vibrating wires will eventually work-harden and part.
On my 2000 wagon, it's inside a plastic box (which is taped shut), which in turn is inserted into a kind of holster on the side of the battery tray, a long side that's as tall as the battery case. It's still a bit flobbery, as the battery tray is plastic and not especially stiff.
1986 MT-4 4-cylinder (R.I.P. circa 1990, rust, clutch)
1994 Station Wagon (R.I.P. circa 9/2005)
1991 Station Wagon (R.I.P. 1/2007, but the Benz that pulled out in front was bent much worse)
1998 SE Station Wagon (R.I.P. 2/28/09 at ~186k)
2004 Taurus SE w/Vulcan & AX4N | dark shadow gray metallic | gray cloth interior | still strong at 192K+
2000 Taurus SE wagon w/Vulcan & AX4S / tropic green metallic | gray cloth interior | purchased 6/12 at 51k miles