The bottom strut bolts are 7/8 or 21/22mm if I recall correctly. S is right, they are torqued to about 180 ft lbs as I had to take them off to do my wheel bearings last year.

You'll need a box wrench (big one) to hold the bolt and get the biggest breaker bar from Harbor Freight you can find (I think biggest is like 25" and 1/2" drive) and put a socket on that nut and crank 'er loose.

Drinking a bottle of Muscle Milk beforehand will help, and its up to you but the bottom strut bolts are stretch bolts supposedly so I bought 2 new ones and 2 nuts from the dealer when I reinstalled after I was done with the bearings. I torqued to 150 and then an 1/8 turn more as my torque wrench only goes up to 150.

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2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards