out enough about it to drive it but there's two knobs to pull like 
chokes on either side of a twist knob below the middle of the seat.  
The knobs refuse to be pulled and twisting the knob doesn't do anything 
to the motor.  There's no instruction book and a dealer I phoned said 
it's the heater control.
- - - - 

The twist knob is the heater control- twisting it out turns on the heat,
twisting it in turns it off.   That is, only if the cable is not broken, they
 are hooked up to the heater boxes, and all the tubes are in place.

the one to the left of the twister is the choke - for buses that came with
36hp motors - before chassis # 469 447 - may 19,  1959.   are you sure you
have a '60?   this is irrelevant unless you have a 36hp motor is the bus.

the one  to the right is the gas reserve switch.   for post-barndoor  buses
that came before gas guages.
  this is further towards the middle of the bus, unless you have a walk -
through.  if not used, it may have rusted up.   these buses came with a
stopcock that could be set to on, off, or reserve (pull the switch all the
way out for a couple more gallons)

the control knob for auxiliary gas heaters is also placed to the right of the
twist knob, if you have one.

hope this helps  :)