OEM droplink rods have the ball joint that attaches to the drop arm crimped into place so that it cannot be removed, as I found out last month! I bought aftermarket, prolly, not in the UK so can't look at the box! cost me about £100.
Doing the front one won't affect the tracking as the rear one keeps it tracked, But DON'T lock the steering wheel when you put your new one on as if the wheels have moved it could be set too far out to be adjustable without taking it all off again, as I found out!!
(compared the lengths and set the new one to exactly the same as the old one, which should have been ok, then locked the steering wheel. It wouldn't fit so I assumed I'd made a boo-boo, and wound the outer BJ out another coupla turns. Put it back together, took it for a spin and the steering wheel was 45 degs out!) so much for the Haynes method!
The wheels must have moved unbeknownst to me, so back under, wind it back in again, slight readjustment on the outer end and back in it went perfectly straight.
But if I was doing the rear one, I'd be very careful about getting the length exactly right. And/or budget for a tracking session.