This is the cast Zinc (zamak) version and probably the most common version. I also guess that it would have been the later version as cast zinc would be cheaper to manufacture.
There are a couple of things to look for:
    There are horizontal grooves in the handle.
    The text on the underside is raized.
The adjustability is the same - it has the strong centre spring that pushes the blade against the topcap.
They also don't have lather grooves so need more rinsing than other razors.