Yes they have them. They are in the engine bay on the left side in the 2.5 models but the location isn't listed for the 2.7 in the GC.
FUEL FILTER / WATER SEPARATOR
DESCRIPTION
In order to assure trouble free operation with winter
grade diesel fuel, a preheater valve is located
with in the fuel filter. Depending on the temperature
of the heated return flow fuel, fuel flows back
through the preheating valve into the fuel filter to
heat up or flows directly back into the fuel tank.
OPERATION
PRE - HEATING Up to 45°C (113°F), the thermo
bimetal plate of the preheater, shuts off the return
fuel flow port to the fuel tank. The fuel from the rail
flows into the fuel filter to be warmed. If there is air
in the system, a ball seals off a port and the air is
directed to the fuel tank.
NON PRE - HEATING From above 45°C (113°F)
the thermo bimetal plate of the preheater, shuts off
the port to the fuel filter and fuel from the rail flows
directly into the return flow line to the fuel tank.
REMOVAL
WARNING: NO SPARKS, OPEN FLAMES OR SMOKING.
RISK OF POISONING FROM INHALING AND
SWALLOWING FUEL. RISK OF INJURY TO EYES
AND SKIN FROM CONTACT WITH FUEL. POUR
FUELS ONLY INTO SUITABLE AND APPROPRIATELY
MARKED CONTAINERS. WEAR PROTECTIVE
CLOTHING.
(1) Disconnect negative battery cable.
(2) Insert a suitable hose into the fuel drain port
in rear of filter, turn drain port counterclockwise and
drain fuel into a suitable and appropriately marked
container.
(3) Disconnect fuel feed and return lines at fuel filter
and set aside.
(4) Disconnect fuel heater electrical connector at
fuel filter.
(5) Remove fuel filter retaining bracket bolt and
remove fuel filter.
INSTALLATION
WARNING: NO SPARKS, OPEN FLAMES OR SMOKING.
RISK OF POISONING FROM INHALING AND
SWALLOWING FUEL. RISK OF INJURY TO EYES
AND SKIN FROM CONTACT WITH FUEL. POUR
FUELS ONLY INTO SUITABLE AND APPROPRIATELY
MARKED CONTAINERS. WEAR PROTECTIVE
CLOTHING.
NOTE: Assure fuel filter drain port is closed.
(1) Connect fuel heater electrical connector.
(2) Position fuel filter in bracket and tighten
retaining bolt.
(3) Connect fuel feed and return lines.
(4) Connect negative battery cable.
(5) Start engine and inspect for leaks.
