Photo of the 4 tube units with tubes installed. From left to right: (?? no markings) / IN-306 / AM-308 / AM-3(?)23. Note that the unit with no markings has a cap kludged to the side. Click for larger view
Photo of the 10 tube units with NO tubes installed. From left to right: AM-320 / IN-501 / (no marking) / AM-3(?)23 / IN-501 / TR-307 / CF-311 / AM-306 / AM-312 / IN-307. Click for larger view
The subject of this thread will be the
Ebay auction for the "Mark 1" tubes from 1951....
http://www.ebay.com/itm/...BE-MODULE-/131073757653 ... After doing research I decided they are from an early IBM Mainframe such as the 650 (1951-1955) but not Mark 1. It is possible that they could be from an earlier machine. If you're interested I found these pages that go into similar units owned by others.