If it is Hy-Gain, you should be able to find the part number on some of the parts -- the element support clamps should have a part number on them, for example.
Many Hy-Gain antennas use the same parts, but you should be able to take a look at what you have and compare it to the parts list on the Hy-Gain antennas and identify what you have it is Hy-Gain.
You can find the parts list, manual, and ordering information for missing parts on the Hy-Gain site.
www.hy-gain.com/