Basically, I would like it if they served on WWII and disappeared in 1951. Most of them would have been roughly 40 to 45 at that point. They stayed there until around Year Seven of the “Age if Heroes”, which would be around the time of, you guessed it, The Armageddon whatsis mini where they came back, having barely aged at all. Since, by basic Rebirthesque timeline calculations, that was roughly 11 years ago, these guys would be early to mid 60s. Obviously, they were erased from memory due to Flashpoint, so when they come back, the whole of Earth 0 remembers them ala Wally the red.