That is a reproduction antenna but it should work and looks like the original. I just got the same one from NPD to use on my 66 Hardtop. NOS antennas are very expensive. If you use the search feature of the forum you will find many posts about antennas, some good, some not so much. An original has the script FOMOCO in an oval on the antenna base, but it is not visible when installed. The same logo is present on the retaining piece also not visible when installed. All of the chrome plated external pieces I have, the sleeve and nut, I believe are aftermarket as they have no identification marks. Most of the originals were pitted so I tossed them. Another identification feature is the plug to the radio. The cable has a very sharp angle into the plug and is held in position with a support that is crimped inside the plug. I don't think the cable is marked.
Jim