I have recently purchased a 1965 GT that was rebodied into a 1966. Recently while driving, I noticed that it would kind of stutter when starting from the stopped position. Once going, it seems to shift fine from 1st to 2nd gear, however when it should shift to 3rd, it just revs up and doesnt shift. Any insight on what the problem might be? I am hoping that I will not have to rebuild or replace the transmission and hope that it might be a small problem. Any help will be greatly appreciated.