It's not going to make a difference I believe. Are you not the first owner? I don't remember from my research Ford using asymmetrical styles of UCAs. I am about to do the UCAs on my Ranger and after research I've discovered some people replace one side at a time and will replace with their preferred style of part (pre-greased, w/ grease fittings, or two-piece). I don't think it'll hurt having different ones.
I got my parts cheap so I just got the same for both sides, one-piece, and will replace them at the same time. I suppose you can replace one at a time but I would make sure its the same style as the other one.