I did a whole lot of boat work before the depression hit here.  I replaced many more combiners than I replaced isolators.  
Adding and isolator to any truck no made for it will be a serious tear-up and it would void any warranty.  
Are you sure it is an Isolator and not a Combiner?  
In the years since, I have only seen one truck with an isolator.  I have seen many with combiners.  The combiners all have contacts.  Those contacts fail.  Isolators require that the main engine alternator have a remote sensing capability.  
Matt