I am going through an inherited motherlode of old (60's?-70's-80's-90's) components. I am pulling the datasheets for all of them so I know what they are. One thing that I keep running into is that the part I am searching for may be so obsolete that I can't find it. I have found that if I change the manufacturer, I can find the datasheet. For example: I have a bunch of ECG4069. I cannot find ECG4069 anywhere; I assume it went obsolete before the advent of the internet. If I change the part number to NTE4069, I can find a datasheet that describes a High Voltage Hex Inverter. Are they the same thing? Can I use that datasheet to confirm the part I have? Do manufacturers use the same part numbers for the same IC? or is it possible that they might use the same part number to describe 2 totally different parts?