1985 745t

Took the brick to get the snows on and have the alignment done at my tire place. Alignment guy said the front left outer tie rod is lose and needs to be replaced... can't align it with the play it has now.

My question is if the tie rods are a "replace one replace both" item? I know things like ball joints generally are, and I figure it's cheap anyway so there's no reason not too, but I'm wondering if you have to or should replace both tie rods of a type (outer/inner) when you replace one to maintain evenstability, wear, etc. between sides.

BTW, when he says theres play he is, I imagine, referring to the ball joint looking section of the outer tie rod? I don't imagine there could really be much play in the other end since its justa thread (play would equal stripped).

Thanks,
rt