72 overcharging

I believe so. What you want to find out is "if" the VR supply voltage (the IGN terminal) is same as battery. You want the key in "run" with engine stopped. Now measure from battery positive to the VR IGN terminal "or as close as you can get."

Another way to look at this is (with key in "run") to measure battery positive to engine block and note the reading. Then measure from VR IGN terminal "as close as you can get" to engine block and note that reading and subtract the two. Another place to measure the VR is the blue field wire at the alternator. You must NOT disconnect anything to do this measurement. Leave everything connected and 'back probe' the connector