Tag indicates that is was previously owned by GMC, GM Instrumentation Laboratory, GMC Truck and Coach Div. I removed then reassembled the heads to verify that the diaphragms are sound.
The plastic tube that joins the vacuum heads is a bit kinked. It does not seem to currently impact the performance, but the tube should probably be reinforced or replaced.
The item "Thomas 2737CM39 TFE Vacuum Air Pump Leeson A4S17DZ11C 1/3 HP 110V Electric Motor" is in sale since Saturday, January 28, 2017. This item is in the category "Business & Industrial\Hydraulics, Pneumatics & Pumps\Pumps & Pump Accessories\Vacuum Pumps\Other Vacuum Pumps".
The seller is "sbachman-mi" and is located in Ann Arbor, Michigan. This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, China, Sweden, South Korea, Taiwan, Thailand, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Israel, Mexico, New Zealand, Philippines, Singapore, Switzerland, Norway, United arab emirates, Qatar, Kuwait, Bahrain, Croatia, Malaysia.