The '02 Tahoe I just bought has 98,000 miles on and I haven't the slightest idea if the plugs & plug wires have ever been changed so I figured I would upgrade the plugs and wires. I went to the Summit web page and entered my year, make and model. I ordered the AC Delco 41-985 Iridium plugs and the 8 mm Summit wires that were listed for my vehicle. The online catalog had no mention that I saw about the length. After they were shipped, I got an order confirmation that said "LS Wire Set (long) 8mm". Then in the specs it said 12 1/2". I said "Oh Crap!" and ran outside and pulled one of my wires, and of course they were 9 1/2". When I called them they said that the only GM wires listed that are 9 1/2" are for the Camaro and Firebird, and the only wires listed for the 2000-2004 Tahoe are 12 1/2". They were good about it, and sent out the right wires (at least I hope so) and said to ship the 12 1/2" wires back.
I also ordered the Taylor braided heat shields to replace the ugly metal oem shieldson the plug wire boots. One end of the braided shields is 1" in diameter but the hole in the other end is only big enough to get a bare wire through, so those got sent back too. They must only be to slip on the wire when you put the ends on yourself. Oh well, it sure sounded good to begin with.
To make a long story short, make sure you measure your wires before ordering. I've never heard this subject mentioned in the forums either, but then I've been known to miss stuff before.