For speakers, there isn't any real polarity. Just make sure you hook the positive wire on the the same side on both speakers, left for instance. As long as you have them both the same, you will be fine.
(sometimes the positive is marked in small letters or with a dot of paint, but as long as the speakers are identical, just hook the positive on the same side of each).
2012 Ford F250 ext. Cab 4x4
2002 Jeep Wrangler Sahara
2008 Yamaha V-Star 650 Classic
2008 Work and Play 18LT