Found some REAL antiques!

So, I recently bought my Dad's old pickup (2000 green Chevy pickup) when he got his new one, and I'm going to sell my current one (the 1994 red Chevy pickup) which I also bought from my dad. I was cleaning up/cleaning out my old truck, and transferring stuff to the new one. I went to grab the flares that had always ridden in the back, and was about to move them over, when I noticed the box was a little mildewed. No big deal, I can get more, right? Plus, the box said something to the effect of "manufacturer recommends replacing every year." But in the meantime, I did what any red blooded pyromaniac would do, which is to light them off in our driveway. As I pulled them out of the box, I saw that they were a bit distended, and one was split open. I also saw something else interesting. The date (presumably) of manufacture. 

JULY 1978

So, I have to ask. Did these ride around in my Dad's 1976 yellow Chevy pickup truck, his 1983 blue Chevy pickup truck, the 1994 red Chevy pickup truck, and ALMOST made it into the 2000 green one? They were literally older than me by about two months.

I have an email out to my Dad, and I'll see what he says!