part numbers 334227 rear & 334228 front
summitracing.com $64.95 $64.95
rockauto.com $55.79 $49.79
shockwarehouse.com $72.24 $65.37
The Grandprix and Monte Carlo
FYI, A lot of 2000-2004 Monte Carlo parts are the same as the Grand Prix.
http://www.pfyc.com/c/04/2004-2008+Pontiac+Grand+Prix+04+Accessories+Store.html is another outlet to find part numbers, then search other websites as their prices are rather high
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03 GT, STB, GM HD sway bars, 35% tint, GE893(37watt)fogs, Flowtech Terminators, 180 T-stat, ZZP DP & PCM, Ceramic PLOG & Crossover, 18" glasspack, 2007 17" Mustang Bullits 235/55/17 Pirelli PZero Nero, 12" R1 D\S rotors, gutted air box, GTP radiator