LEGO 6688 Ambulance

6688 Ambulance is an emergency-themed set released in 1985 under System. It includes an ambulance, a stretcher and two minifigures, a medic and a patient. The medic apparently also has to drive the ambulance, since there is no dedicated driver. This is a different set from the older stretcher model, with small wheels. Newer sets have the stretcher without wheels on the bottom instead.

Other ambulances
LEGO 6680 Ambulance (1981)
LEGO 6666 Ambulance (1994)
LEGO 7890 Ambulance (2006)
LEGO 6380 Emergency Treatment Center
LEGO 3832 The Emergency Room