First of all, thanks for this. It's advanced things a long way, and I'm chargin now. The significant voltage drop turned out to be between the alternator ground wire connector and the manifold. There's a metal bracket between the manifold and the bolt head and this wasn't fitting (wouldn't fit) snugly to the manifold. Thus although the ground wire connector was tightly bolted on, that was only to something that didn't provide enough ground. So I put the connector inside the bracket and threw in a washer for good measure. Voltage loss on the negative side is now down to right around 0.2V, which is at the limits of acceptable. I'll root around for the source of that loss. I still have my 0.5-0.8V loss on the positive side. Maybe a bad crimp somewhere?

Thanks to all for input. I've learned a lot. Is this claim right - if you measure at least 14V at idle between the alternator output stud and the casing, the alternator is functioning correctly? If it is, I don't know why it isn't the first thing anyone measures. If not, why not?

Thanks again.

Andrew