Ford 2000 Explorer Owner's Manual page 206

Roadside emergencies
3. Connect the negative (-) cable to the negative (-) terminal of the
assisting battery.
4. Make the final connection of the negative (-) cable to an exposed
metal part of the stalled vehicle's engine, away from the battery and the
carburetor/fuel injection system.
Do not use fuel lines, engine rocker covers or the intake manifold as
grounding points.
Do not connect the end of the second cable to the negative (-)
terminal of the battery to be jumped. A spark may cause an
explosion of the gases that surround the battery.
Engines except 4.0L SOHC
206