i Have 2 alts in my yukon and have the heavy duty fuse holders from SSA red or blue. the Main alt has the XS power VCM,also not using the stock harness, i went ahead and BY passed the stock harness with a relay . now the second alt is just wired in to the same relay system that the main alt is using. i ran a ground (-) on each alt straight back to the Battery's in the rear and the Positive (+) power cable from each alt as well. i am doing fine so far. but i do need to by the harness that will tie into the Xs power VCM sooner or later to control the voltege on both alts at the same time 2 350A singer alts 5 XSPOWER XP 3000 Batts 1 AMPERE AUDIO 8.0 TFE 4 SSA EVIL 18's