i recently have been having a harder and harder time going into third at high rpm . someone sudgested my synchro is gone.
what is a synchro, and how much to fix it.

 

Synchros are the things that help you change gears. You can drive without them, but it makes it harder and if you force it into gear you could easily blow your entire transmission. If you're having serious difficulty with changing gears then I suggest that you replace your synchros immediately. I'm not sure how much it is...a lot considering the mechanic has to take apart the transmission to install them.