To change the 3 rear spark plugs on the V 6 engine you need the following tools and parts,
10mm ring spanner,
12mm ring spanner,
Ratchet drive for the sockets and extension,
5/8 spark plug socket,
Small flat blade screwdriver,
3x Platinum Sparkplugs ( PFR6G 11),
Intake gasket. (MD175776)
1 Disconnect and remove the battery from the car.
2 Remove the air duct between the air flow meter and the throttle body.
3 Undo the 2 bolts on either side of the manifold releasing the electrical connectors.
4 Undo the 2 bolts holding the throttle cable support bracket and earth straps.
5 Slide off the 3 vacuum pipes at the throttle body end of the manifold.
6 Unclip the electrical connectors on the step motors
7 Undo the 4 x 12mm head bolts at the back of the manifold.
8 Undo and remove the 5 bolts and 2 nuts and washers from the front of the manifold.
9 Carefully lift the manifold up over the studs and while turning the manifold counter clockwise place it where the battery usually sits.
10 Place a cover over the inlet to stop anything from falling into it.
There is no requirement to disconnect the water hoses.
11 Remove the spark plug lead/covers and remove the spark plug.
Replace with new Platinum plugs
Read more: http://wiki.answers.com/Q/How_do_you_change_the_rear_bank_of_spark_plugs_on_mitsubishi_fto_gpx#ixzz19SvpPKdD