I installed a Vintage Air system in my '56 3100. This was my first time adding AC to anything and I think it went pretty good, as I recall I had to convert the lowest mounting bolt to a stud to make things easier. All the bent lines fit without issues. I mocked up all of the flex lines and had my local auto mechanic crimp the fittings on and then charge the system after I finished the installation...that was about 6-7 years ago and it still work great!
I don't have any experience with Old Air.
Mike B
