Any numbers or letters, words on the valve or valve solenoid at all?

Nothing at all that I can find.

What brand is the irrigation timer and sprinkler heads?

The irrigation timer has been replaced. We have a Hunter with remote. I don't remember what it was originally. We use Hunter lawn pop ups, and the remainder of the system is drip, with DIG emitters.

It looks like an Irritrol 205. But I'm thinking if its as old as the house more likely a Richdel 205?
http://sunshoweronline.com.au/irritrol-richdel-205-solenoid-valve-25mm-inc--flow-cont-

That solenoid in the picture, though, is very different from the current 205 solenoid, and I know there is not a direct Richdel replacement. Because of its age you could try the R811 solenoid from Irritrol, but I know for most Richdel models pieces need to be removed (o-rings or white plastic pieces) in order for the new solenoid to fit.

Otherwise you might be sol on this one lol.

Thank you!!!