camaromikey,
I installed a used one in my 55 Nomad a few years ago because it was my commute car and I wanted to get 20MPG out of it. 150 miles a day added up in gas.
Worked like a charm. I reved at 2500 RPM at 75 MPH and got just over 20 MPG! Never had a problem with the gears, but I HIGHLY recommend you have them installed by a professional.
Ed