How to tell gear ratio of individual synchros ??

["Verne Harris (Fnugen)" <vwman@skyia.com>]

How do I know if I am looking at a 2.12 2nd synchro ?? I have to rebuild a tranny to replace my now blown-up tranny........and I have a 4k.......but the 2nd is shot in it. So, I need to be sure the the replacement gear is in fact the 2.12.      Any help is grrrrrrrrrrrreatly appreciated.

 
       Verne :
     '84 Wolfsburg 8v Roc
     '91 Passat GL (Wife's car)
     '97 Norco Lobos Comp (Full-susp)
     '89 Wicked Fat Chance...gone but not forgotten.
     '93 Scott Boulder
     http://www.skyia.com/~vwman/h2ovw.htm     <---my car and general pics
     http://www.geocities.com/MotorCity/Track/2830/   <---A1 pics only !!!!