4 Terminal Key/Fwrd/Reverse switch
 

Im helping a friend who is restoring an 80 DE-4. The cart is running great but want to get the reverse buzzer going. Looking at the diagrams the key switch should be a 4 terminal and what is currently in it is a 3. The only place that even has a pic of one is vintage carts but they are no longer available of course. Does anyone know a source for these or possibly a suitable replacement. The 4th terminal basically would provide 36v when in reverse only for the buzzer. Thanks in advance.