Back in the day of the overdrives, continuous on relays were not commonly available. I tried a headlight relays back in the 60's and and they only lasted about a week. The Bosch or Hella relays have only been available here the last 20 years or so. I have never tried one, but our trucks now have a bank of 20 or so relays and they almost never fail. They even power electric wipers. Here is a schematic of how the overdrives were wired.
http://picasaweb.google.com/crenwel...N9tJKHsYFELgbeyFTDgw#5431562618455431554 I would think that a Bosch type would work. However, I remember from taking an OD relay apart, they had a light and a heavy winding. It seems like the heavy winding was to energize the solenoid and the light winding was to keep it engaged, but I'm not sure.
