I put one in a 73 Dart 2 years ago , I driven about 4 thousand miles with no issues. As far as the install.....take out the seat and carpet , you will have to cut a small piece out of the tunnel to make it wider. Get a new driveshaft, well worth it , I put the control box under the drivers side kick panel.
Just put about 500 miles on it the past weekend
70mph 2500 RPM 3.55 gears.
On of the two best investments I did to the car.