I believe mine were 1/2". I sprayed mine twice a day for 4 days. The 115K miles of rust were stubborn, but gave up in the end. Also make sure you are using a 6 point socket, the 12 point may round off the nuts.
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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