According to the shop manual all the 4wd soobs had the Hitachi in 83. I did notice the curve in the Nippondenso vacuum advance arm. It is straight on the Hitachi. I don't know what difference that would make but when mine starts dogging out and loses all spark at 2500 or so RPM, it does sound like the vacuum advance is not working properly. That was the first thing I checked but it seemed to be ok. I am hoping once I figure out this wiring the Hitachi will solve the problem.