I was wondering the same thing... I was at Pick-N-Pull and saw the thick plug wires (mine are skinny) and was wondering whether to replace mine.
Now I think I'll keep the skinny ones on my truck and use the thick ones as a spare.....
'92 Runner SR5 3.0 (mfg 11/91) bought 4/07 in Portland, OR
fire engine red
112,000 original miles as of 10/2009
The BEST mod was garaging it in California, rather than Michigan.
Mods: Deckplate mod; Downey 1.5" rear lift with spacers, new springs & shocks; 750W inverter with power strip; ProLock anti-theft, Pioneer deck w/tweeters, rear door speakers, rear 12"s; Hilux Altimeter/tilt gauge (wired into the climate control light); Magnaflow exhaust; Garmin GPS; Thule roof basket w/Hella lights.