For 6A6 (DUAL CRANKING 730 CCA BATTERIES), it is dual batteries setting with parallel connection without isolator relay in 2007 model.
5W4 (IDENTIFIER FOR SPECIAL SERVICE VEHICLE) is a Pro Code for police option package, which includes following options:
(K47) high-capacity air cleaner,
(KW7) 170 amps high output alternator,
(K4B) 730 cold-cranking amp auxiliary battery, electrical power and vehicle signals for customer connection located at the center front floor, auxiliary
battery circuit for customer connection located in the rear cargo area,
(UN9) radio suppression package,
(NZZ) underbody shield, delete roof rails,
(ATD) third row seat delete and
(NQH) active 2-speed transfer case.