Cat 267b injection pump timing

Hi, I am trying to adjust the injection timing on my cat 267b. I had the head milled, so now I have to adjust the timing. I was following the service manual on the procedure, but when I go to loosen the injection pump, where there is supposed to be a nut, there is just a round thing, with no place to put a wrench on. See pictures below. One picture has the nut on the one side, like it supposed to be, the other doesn't. Not sure how to loosen the pump to adjust timing now...