How a $1.50 part can cost $2000

Another member GTXexperience just went through the same thing!He soaked it numerous times with lubricant over days and got his out!Here,s some suggestions..
Hit hard with hammer after spraying down and use Vise-grips
Try welding another bolt to it(heat might penatrate it to crack loose,)
Pry caseing off with big screwdrivers
Soak it for days,spray down a few times a day with numerous lubricants!

Gotta try something!Hope you get it off!Don,t forget to put antisieze when replacing bolts.