Well after owning a diesel truck since 93 I finaly fell victum to fuel gelling on the road.... Had it happen on off road stuff but never on the road. Well I can tell you first had that the duramax fuel heater can't help you if your introuble already..... It will only heat enough fuel to run at 1800 rpm with light load and it was slowing down ! Never use so much heat that you cant hold any part of the fuel filter housing in your hand...I melted a plastic piece in the primer section! NONE of the parts are replaceable threw GM.... It must be replaced as a hole filter assembly to the tune of $500.00 list cost!!!! and good luck finding one ,it only can come from the factory that its made in..... NO stock IN ANY GM warehouse ANYWHERE!!!!! I talked to 1 dealer in VT that had one and by 8:30 am he had 10 calls on it that day! If any one has any idea who make the filer assembly I would like to get just the parts I need threw them ! I got the truck up and running with a little clean up work with a dremel tool on the parts that melted ,It just started to melt around some "o"ring seals in the primer bulb!Once it cooled off it was leaking fuel around the bulb and drawing air in ! I found the o rings witch are more like lip seals had plastic stuck around them ... I removed the lip seals and cleaned off the plastic and reasembled the filter houseing and vacuemed tested it to 20"..... I got lucky to say the least!