the we have buss bars upfront and in the bed on the batteries, the way we have it wired went as so
3+ runs from front buss bars to the rear, 3 runs OFF the alts ( one from each ) into the rear, a power run off each alt, to the front buss bar. for a total of 6 or so runs of positive into the rear, 4 or 5 ground runs from buss bar to the batts. then engine grounds, and front buss bar grounds to the frame. and then grounded the batts in the rear to the frame also.