18 volts!! has fried a turn signal and 2 inverters

[5Toyota]

ONE of the grounds org used standing in front on right rear corner of the head should be a black wire from block to firewall. in your case i dont think this is the big problem but it should be on there. you could have a problem in the wiring for the regulator that could say regulator when it is the wires to the regulator. on the 1977 78 you could get and use eather the mechinacl or solid state type. for i dont know . about your year. i had a grage once put the wrong alteranter and reg on a Datsun i had came with a 6o amp and they put on a 35 amp and the wrong reg the charge light was on the alt was not even the same case size. and that car was picky no after market xternal regulaters ever worked on it only a genuine Datsun factory one they said they would work it fit but they did not work.