Auto Parts Fast at RockAuto
give this place a look. found what I needed for my front end . . hope it helps
It will be interesting to see if they are correct numbers-- They list 4 different spark plugs for an 03 diesel. Should I get the standard or or pay the extra for platinum?

I've neglected to change mine thus far.
<TABLE class=main style="BORDER-RIGHT: 2px groove; BORDER-TOP: 2px groove; BORDER-LEFT: 2px groove; BORDER-BOTTOM: 2px groove; BACKGROUND-COLOR: white"><TBODY><TR><TD class=center style="FONT-WEIGHT: bold" colSpan=5><TABLE class=layout><TBODY><TR><TD class=left>
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</TD><TD class=center style="WIDTH: 95%">2003 DODGE RAM 3500 PICKUP 5. 9L 359cid L6 DIESEL FI Turbo (C) : Ignition : Spark Plug
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</TD></TR></TBODY></TABLE></TD></TR><TR><TH>Item</TH><TH>Price</TH><TH>Core</TH><TH>Total</TH><TH>
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</TH></TR><TR class=part0 id=table328part0><TD><TABLE class=parts><TBODY><TR><TD class=left><TABLE class=layout><TBODY><TR><TD>NGK Part # 4291 {V-Power Plug #ZFR6F11}
{. 044 gap}
</TD></TR><TR><TD>** Sold in packs of 4; Price reflects cost of each individual item, not the pack **</TD></TR></TBODY></TABLE><TD class=right style="HEIGHT: 40px">
</TD></TR></TBODY></TABLE></TD><TD class=center id=node328part0price>$2. 20</TD><TD class=center id=node328part0core>$0. 00</TD><TD class=center id=node328part0total>$2. 20</TD><TD class=center>
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</TD></TR><TR class=part1 id=table328part1><TD><TABLE class=parts><TBODY><TR><TD class=left><TABLE class=layout><TBODY><TR><TD>NGK Part # 7100 {GP-Series Plug #ZFR6FGP}
{. 044 gap}
</TD></TR><TR><TD>** Sold in packs of 4; Price reflects cost of each individual item, not the pack **</TD></TR></TBODY></TABLE><TD class=right style="HEIGHT: 40px">
</TD></TR></TBODY></TABLE></TD><TD class=center id=node328part1price>$2. 42</TD><TD class=center id=node328part1core>$0. 00</TD><TD class=center id=node328part1total>$2. 42</TD><TD class=center>
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</TD></TR><TR class=part0 id=table328part2><TD><TABLE class=parts><TBODY><TR><TD class=left><TABLE class=layout><TBODY><TR><TD>NGK Part # 6441 {IX-Series Plug #ZFR6FIX11}
{. 044 gap}
</TD></TR><TR><TD>** Sold in packs of 4; Price reflects cost of each individual item, not the pack **</TD></TR></TBODY></TABLE><TD class=right style="HEIGHT: 40px">
</TD></TR></TBODY></TABLE></TD><TD class=center id=node328part2price>$6. 58</TD><TD class=center id=node328part2core>$0. 00</TD><TD class=center id=node328part2total>$6. 58</TD><TD class=center>
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</TD></TR><TR class=part1 id=table328part3><TD><TABLE class=parts><TBODY><TR><TD class=left><TABLE class=layout><TBODY><TR><TD>NGK Part # 3271 {Platinum Plug #PZFR6F11}
{. 044 gap}
</TD></TR><TR><TD>** Sold in packs of 4; Price reflects cost of each individual item, not the pack **</TD></TR></TBODY></TABLE><TD class=right style="HEIGHT: 40px">
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</TD></TR></TBODY></TABLE></TD><TD class=center id=node328part3price>$11. 09</TD><TD class=center id=node328part3core>$0. 00</TD><TD class=center id=node328part3total>$11. 09</TD><TD class=center>
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</TD></TR></TBODY></TABLE>