What 4spd trans is a good fit for a '66 Chevy ll/SS? What Muncie is factory for this year? Differences of close and long simply the actual travel of the gear shift? M20 pros and cons, M21 pros and cons? A individual here on this site has a 4spd for sale out of his numbers matching Chevy ll/SS 2000mi since rebuild for $1600 OBO...