The YF for the AMC/Jeep 258 engine has slotted bolt holes in the throttle body flange, so it will fit both of the common stud spacing dimensions without any modification to the carburetor. The same carb is also specified for the 232 AMC six, so it appears to be sort of a "universal fit" application that might require a little jet or metering rod tuning for best performance. The vacuum ports in the throttle base DO NOT have the same spacing as a Rochester B, so be sure you get the correct gasket for the carb, or you can block off one or more vacuum passages.
Jerry

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