I'm shocked that all of the post above seem to indicate Pertronics is only available for 1964-73 distributors. I sell more 1974-77 Pertronics than I sell 1964-73. We originall offered the Crane unit until we discovered the Pertronics. The Crane units were so fragile that we could accidently break them while installing. Once installed, they were flimsy, they would wobble when touched. The Pertronics mounts rigidly, and is fully self contained inside the distributor. Plenty of good testimonials above, I don't need to go into that.