That little hose section behind the fan pulley is the turbo coolant supply. I've replaced mine twice, as well as a bunch of others. Not too complicated or difficult (replaced one in an RV park in less than an hour, once). I prefer the OEM spring clamps, as well, but used screw clamps the last time I replaced the line. I double-clamped it (4 clamps, 2 at each end), and it hasn't leaked since. I reused the OEM spring clamps the first time, and it began weeping rather quickly. As far as I know, mine wasn't/isn't pressurizing the coolant system, such as with a head gasket leak. GM/Duramax surely could have located the soft connection in a better place.