Classic/Antique Car Repair: transmission, speedometer cable, chevy car

Question
I have a 1969 chevelle with a 350 turbo transmission that we drove and when we came to a stop then started again there was nothing, just reved.  It wu=ill not go into any gear, the housing moves but nothing.  I noticed the speedometer cable was not connected, could this be the problem?

Answer
Sorry, but I don't know anything about your car.  I am a Model A guy.   Anyway, it is not a serious problem.  A trans shop should be able to fix it quite easily.  The speedo cable has nothing to do with it.  It may be low on fluid, but if it is, there must be a reason it is low.  Check that and add some if it is low and see what happens.  Be sure to put the correct fluid in it.  GM does not use the same fluid as other car companies.  I assume it won't go in reverse either.  
Find you a chevy car club and join it.  They will have all the answers and be happy to help you.  They will also know where to get it fixed.  
Good luck and have fun with that car.
jack