Don't worry about accuracy yet. The only way to get the same readings printed in the manual is to use the same meter they used to get those readings.
First step is to check the alternator stator for continuity between the windings and for shorts between the windings and ground. Disconnect the wires from the alternator where it plugs into the wiring harness or rectifier. Alternate method; disconnect the rectifier where it plugs into the wiring harness. Use the meter on the ohms scale to check for continuity between any pair of the 3 same colored wires (usually white or yellow) going to the alternator. You should have continuity and the reading should be approximately the same value. Now check for continuity between each of the 3 wires and ground (engine case or cylinder fin). There should none.
Let me know what you discover and we'll move on to the next step.