Toyota Repair: 84 toyota pickup charging problem, model trucks, toyota pickup

Question
I have a 1984 Toyota pickup 4x4. It stopped charging the battery so we checked the alternator which was putting out 1.9 volts so I got a new alternaor. The new alternator puts out 12 volts at the alternator but at the battery its getting 18 volts. I thought the IC regulator was bad so I replaced it and still the same thing, 12 volts at the alternator and 18 volts at the battery. The charge light on the dash stays on all the time. I can turn on the air conditioner and it drops down to around 13 to 14 volts at the battery. I have checked all fuses ( under the hood, under the dash, bhind the glovebox) is there anything else I should check?  

Answer
Some of the early model trucks had an external voltage regulator and there is no IC regulator built into the alternator, make sure that it's the correct alternator, check for an external regulator. If there is an external regulator get an alternator that is a non IC regulator type.