I asked a dealer and he said only way to get duals was to factory order, but I can't imagine a separate wiring harness just for dual alternators. I am thinking about adding a 16.5 electric winch and 150 amps isn't enough to keep up. Duals would be the way to go. I installed a 200 amp on my 02 and my 12k winch made it get very hot, then I switched to a hydraulic winch.
2017 3500HD CCLB Black on Black LTZ Loaded L5P, Banks Derringer with I dash, Ranch Hand bumper with 18K superwinch talon, Curt 20k puck hitch, 60 gallon aluminum transfer tank with electric pump, Onan Quiet Diesel 5500 for extra weight in the bed, Cooper STT PRO 285/65R18 and Vision Manic wheels. 2nd set of tires and wheels, Cepek Trail Country EXP 285/65R18 on Ultra Predator II Black/Machined 18x9
2018 Solitude 310GK fifth wheel with a 12' Haulmark tag trailer to haul toys in.
1997 Jeep TJ, Currie 8.8 high pinion axles front and rear with ARB air lockers, 4.56, 5 on 5.5 with warn hub kit, Atlas II transfer case with Klune V doubler, 4 inch Currie Lift and 35x12.50x15 Mickey Thompson MTZ on 15x10 Mickey Thompson wheels, Ramsey 9500 winch, hydraulic ram assist steering, on board welder and on board air, custom aluminum fuel tank.