007, Welcome to the best site on the net for these ol trucks.
Ive heard,but havent tried, that the cables and retractors from the 55,6,and 57 chev. stationwagons will work with a little "cobbling". You could probably get a catalog for those years of cars and put your imagineering to work and come up with something. The parts for the 'burbs arent being repro'd,as far as i know, so that may be your only way out. The retractor looks like a tape measure that they forgot to put the numbers on........
Good Luck,
Marty