Home » Tony’s Tips » Articles » Cummins Marine 330B 370B Diamond Gear Cooler upgradeCummins Marine 330B 370B Diamond Gear Cooler upgrade Heavy Duty Cu-Ni Sendure cooler, Class II, Cast Bronze Caps & Fittings w/ Double Zincs 330-370 Diamond Trans Cooler upgrade “Plug & Play” replacement for both the early ( 1.5″ water barbs ) or late 330/370 Diamonds ( 1.75″ water barbs)