John,
If you stick your head inside the passenger rear wheel well until you hit the inner fender, the number should be just under your nose. A little wire brush or sanding might be needed to see it, but it should be there. It won't be nice and deep and even like on a M35 though. I mentally picture some work program Kaiser had for the special ed school down the street from the factory every time I see those numbers. They almost look like a random bunch of numbers on some trucks.

The front number location on the 715 here in my class is on the raised pad an inch or so rear of the passenger side radiator support bolt. Inside the triangle formed by the frame and the frame corner support piece. Again, very weak numbers not lined up and not spaced right.

Hope this helps.