I got this Type 180A Time-Mark Generator in my first batch of Tektronix stuff that I bought from an old retired engineer in town. This one is Serial Number 5733. Here’s a link to the djvu manual: https://www.dropbox.com/s/8aoo0znnlzfuwmt/180a.djvu?dl=0

Let me know if you have any stories about this 180A Time-Mark Generator, or if you are interested in purchasing mine for a reasonable offer.