another dual battery question... original though i promise.. :)

[hereinmissoula]

i have a 1968 k20 that looks like it was camper equipped... this is somewhat of a base model, but does have hd rear springs and a dual battery setup... don't know if factory.. don't think it is... anyway, there is a resistor/transistor/capacator looking thing on my fender with wires from alt and battery going to it.. looks real old

also there is only a small wire coming from the positive on the aux battery...

maybe something use to be there when there was a camper.....

only reason i ask is the wiring is old and i will be replacing it and was thinking of just doing positive to positive....

what is the transistor/isolator??? thing on my fender.. looks like there is two capacators on the top... i will take a pic later and post..

hope this is enough information...

thanks guys