Under the hood - bolted up next to the battery.. (i'm in a gasser with 1 battery on passenger side) there is a some sort of junction box. It has a bolt on one end - it looks like the alternator cable is tied in there. Also it has three "slots" - one of which has a red power cable that goes into a loom (I guess powering electronics )

Anyway - what is this box & since I have two slots free is it possible to get the "Blade" type connectors & use the other slots for accessories (ie.. onboard air compressor) or since the alternator hooks in here if I run a 2nd battery for onboard air (which I am considering) can I plug in here to charge the 2nd battery???

It kind of looks like it is replacing the old style solenoid - at least the way the power cables go into & out of it...

This may be the same on previous yrs.. I just know that it wasn't on my 2001.. I had a firewall solenoid...

 

Bump..........

 

You are correct - it is the high current junction box that handles the alternator. Here is the gasser schematic and diesel schematic to give you an idea of what you need to do:

 

Thanks - Perfect - just what I needed & pictures too!!

 

Got a fancy picture like that for dual alternators?