correct Clunky
the AT button is so you can hold the gears longer when towing or under heavy load
my personal opinion of the DC~DC chargers is - its a fraud, use 1 battery to charge the other battery - hang on, N#1 battery now flat...........................
get the Redarc dual battery system, your Alt will charge the starting battery 1st, then charge the 2nd battery
if your going to run a fridge, etc, have them ALL running off the 2nd battery
winch should run off the starting battery ~ cause your going to have the motor running to winch yourself out of mischief, so your Alt will constantly be re-charging your 1st battery while you winch
while you get the dual battery system fitted - get them to fit your Boost Gauge & a Dawes Valve (to regulate the Boost Pressure) at the same time
also get a "catch can" fitted - you would be surprised at the amount of oil fumes that are clogging your MAF sensor..............
once you have them fitted, then get your exhaust fitted
then get it "tuned" by a reasonable Diesel Tuning centre - maybe head to Perth and go to UFI (United Fuel Injection - Gt Eastern Hwy, Redcliffe)
never ever heard of a silly question, so dont be shy and ask if your not too sure
then you know it will be running "hunky dorry"