Mercedes: rear control arm replacement, rear control arm, impact wrench

Question
Can't get the large bolt started into the captured nut.  Seems aligned tried impact wrench as last resort.  won't start

Answer
David
There is an obvious misalignment somewhere. You man need to use a sharp drift to pre-align the component before trying to insert the bolt.Can you drop the arm enough to run the bolt in to the nut to make sure the threads are not crossed?
Rob