[tucsonjwt]

On dual start batteries for my 454, I ran the secondary battery cable under the sheet metal cover over the core support and secured it to the cover using black zip ties from the underside. I did not care for the look of having the battery cable exposed along the top. If you look up through the grille you can see the cable running along the top, supported by the ties.

I used existing holes in the core support to route the cables to the batteries. I did use aftermarket long battery stud type bolts to attach the secondary battery. I ran the negative cable for the secondary to the primary battery, but you could just run a short cable to the engine block or any handy chassis grounded bolt in the area of the secondary battery.

I used the battery saver mat from LMC on both battery trays. It does raise up the battery enough that the stock short battery hold down bolt does not work, but I got longer bolts from the hardware store and it worked OK.

The secondary battery tends to loose its charge faster than the primary battery - probably because of the voltage drop due to the long battery cables going to it. You should consider getting larger gauge cables for the secondary battery, but those will be expensive and the standard cables for the auto parts store will work. You can have custom cables made by online vendors. With two batteries, lower combined charge is never a problem. I don't drive the truck much so I put the batteries on a charger about once a month.

I was buying Autozone Duralast batteries because they have a no hassle exchange but I recently changed to Costco Interstate batteries which are less expensive and I think the Costco exchange will be just as good.