Black/Red Sub?

A friend of mine got offered a Sub which I have not seen yet supposedly circa 1979. The bezel is a diving bezel that is black on top and red on the bottom like a black/red gmt but does have diver/minute makings on it and not a 12 or 24 graduated bezel.
IE this bezel


A search on the internet shows fakes with that bezel and reproductions of that bezel are on ebay and amazon. The problem is when you search red sub... well you get the desirable ered submariner text variation of the sub.

I just want to get more information on it to see if it is even worth my time to go with him and look at it.

Runaway!

Thanks guys,

Due to the slight difficulty in the google search with a competing same term, I could not get any solid info. So the watch is either fake or someone decided to put this aftermarket bezel on it.

Personally I feel it is not a very attractive watch when done that way.