specs for HP transistor?

I know this is mildly off topic but I've run out of places to look so I'll ask here. Recently I found a bunch of new HP microwave transitors in a pile of surplus scrap. I'd not sure what you call this package but the transistor is about 1/16" in size and it has four leads sticking out radially. Each lead is about 1/4" long. Their part number is TXVT-2101 and I can't find a number remotely like that on HP's or Agilent's websites. A Google search also failed to find anything. Each transistor is in an individual box and each is serial numbered and has the gain written on it. I think they date from about 1983 but I'm not positive about that. They're obviously expensive parts and I'd like to find out more about them. Can anyone help? Joe