What year are these PB Check Valves from?

[72-SS-L48]

Hi Guys,

I have a few of each of these Power Brakes Check Valves. Can you tell me what year(s) are correct for each one. As the picture states, they are a little different.

http://img.photobucket.com/albums/v441/mosportgreen66/IMG_0668.jpg

Thanks,
Dave