Heater box vacuum diaphragm, '75 T'all

[jmbrodsky@domain.elided]

        IH all,
     
                I'm trying to track down a vacuum actuator for the 
     heater core vent flap under the hood of my '75 T'all.  The  
     diaphragm is about 2" across, and about 3" long and resembles a 
     football (American).  It has a vacuum input one side, and a 2-1/2" 
     lever out the other with a 1/8" hole in the end of the lever.  It 
     is a linear pull, meaning it pulls in line (co-axial) with the 
     football shape.  It has two screw tabs that mount it to the side of 
     the heater core box, and is made of black plastic witha steel ring 
     around the center.
     
        Believe it or not it has gotten cold here for Tucson, Arizona.  
     30's at night and 50s days.  My windows fog up and I have to use 
     the A/C to unfog.  I can't get any fresh air through the heater 
     core without this unit.
     
        If anyone can help I'd REALLY appreciate it, all the ones in the 
     yards out here seem to leak vacuum.
     
     
        Thanks a bunch,
     

     -Joel Brodsky

         '76 IHC Scout II 345/tf727
         '75 IHC Travelall 150 4wd 392/tf727  it was 27deg. in the truck
                this morning and I have a 40 minute commute with no      
                heat!  Lord help me.