Well looky here courtesy of Richard.. pics & everything.http://www.route6x6.com/howto/T-20assembly/index.html
If you have to do it without pics. Hold plunger in hand so it faces you. If the band lays to your left it left side. Likewise if it winds to your right it's right side.
Takes some of the pressure off the guys. Don't want their heads to explode.
hopefully their marked. when ever i bought them from R.I they were. just stick them in their tim they fit