I made all the electronics myself, with the help of the internet of course.
I used the front grill/bumper from another kit - a Revell / Monogram '59 Cadillac, since the one with the Ecto-1a had the headlights molded in - impossible to light.
I also made the antenna from stretched sprue, since the one with the kit was way too thick.
A fun but long project!
A few pics and a video in the google+ link.