I would agree that yours looks older than the one I posted.
I agree with 58Yeoman that the one I posted looks like it's from the 70's. The one I posted looks a lot like the one we had at work. I started there in 1986 and it was there when I started.
Yours could be from the 60's or earlier. I wouldn't let that bother me. Those jacks are nice. They are 2 stage, they lift rapidly up to what you are lifting then the second stage takes over and lets you raise up heavy loads easily.
The handle also will lay down flat to the ground for getting far under a vehicle. just lift up on the lever under the cross handle to adjust it to the lower level. leave it in the upper level and you can lower the handle to it's stop and lift the front wheels of the ******** of the ground for ease of maneuvering.
I'm not sure if Blackhawk is still around. I know that most of the better jack companies are gone now. I had heard Hein Werner bought out some of the companies.