I have a 2006 XLT 4x4 v6 4.0.. I went to walmart and was going to get some spark plugs then started to look at them all and noticed they all have different thread length.. what ones would i be looking for to use in my truck. and what is the best kind and what would the gap size be? thanks for all the help ..

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2006 XLT 4.0 SOHC.
air box mod

Go to autozone or some other store and get the motorcraft oem plugs or similar. IMO it's worth the little bit of extra money to get a decent plug. Here is what I bought for mine since they are as good/better than oem and pre-gapped but some people on here aren't a fan of Bosch.

Bosch IR Iridium Fusion Spark Plugs

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2003 Ford Ranger FX4
4.0L SOHC V6 Auto 4x4
K&N Performance Air Filter
Bosch IR Iridium Fusion Spark Plugs

Be careful with bosh plugs. Have heard stories of them coming out.
Stick with motorcraft or autolite plugs.

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Motorcraft.

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YZ the way to be!
The Brotherhood!

Mods to come: Camburg entry 6.0 system. FiberwerkX Fenders and bedsides. Tube bumper.
R.I.P. Jeff Ashton. 1992-2011

is there a certain size i need to be looking for

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2006 XLT 4.0 SOHC.
air box mod

Autozone

Autolite Part Number: 5143 $1.99
Motorcraft Part Number: SP-412

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thanks for all the help

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2006 XLT 4.0 SOHC.
air box mod