Knock the small bit into the car that's snapped off, grease the hole and new one and manhandle into place which can be tricky can be helped by using a block of wood to push with a trolly jack( block on top of axle ) under the axle don't push stupid hard only makes it worse.
Oh and you'll need to remove the springs, remove both lower shock bolts and drop down, lift out springs, be sure to seat them correctly when re fitting or put a mark on them to help
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