Reproduction diaphragm pump that mounts on the front all 67 - 73 Cougar or Mustang Autolite 2V carbs as well as 1967 Autolite 4V Carbs. With today's gas, these commonly fail, especially when sitting for extended periods of time. Complete failure will cause fuel leaks, but many times these will affect performance well before a leak actually starts. Good idea to replace every few years or if sitting for 6 months or more. Replaces Ford Part #: C4AZ-9B559-A.