i've had to remove that bolt to replace one of the 2 smaller torsion bar anchor bolts. that bolt is a pain in the ass to remove. spray down with rust penetrant days in advance, have heat ready because you will probably need to use everything you have to remove it. its a pain!!! my xterra was only 1 year old when i had to remove mine and it was still hard.
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2000 XE 4x4, ARB bumper, 33x10.5 KM2, 3" fabtech SL, Skid Row skidplates, Calmini Sliders.