To expand on Paul WNC's comment about having the original part number, you might be surprised to know that the Chevrolet dealers have an obsolete parts computer. You may have to talk to an experienced parts manager to get them to look up a number. I have done this at two AZ Chevy dealers with varying success. As an example of success, I found 4 spider gears with thrust washers (NOS) for the two speed differential on my 1950 COE. These were located at a dealership in New York state and they had no idea what they were and they sold them to me for a total under $75 which I consider very reasonable. I also obtained a NOS diaphragm for the vacuum shifter for the same differential. This was located at a GMC dealership here in AZ. When you present the number to the parts desk the first reaction you will get is that is not a valid number because it does not have enough digits. You then must ask them to look at their obsolete parts computer and that may get you only a confused look. If that happens then ask to speak to the parts manager. If he/she can't help you go to another dealership.
By the way the parts number publications are available on line at the Keith Hardy Old Chevy manual site.
Good Luck,
Kent
