Answers needed for 1981 240D Problem

[wtr]

I'll try as best as I can to describe my problem. There is a bar running horizontal to the firewall that connects to the left and right control arms.When you shift from forward to reverse the bar moves left and right.It seams to shift the front tires a little when this happens.Now the problem is on the passengers side where the arm attaches to the body under the battery box is loose.I had friend shift it back and forth several times because it was making a popping sound and saw the it was pulling away from the body.It has also rubbed a hole in the firewall that you can see from inside the car looking up under the glove compartment.How hard a fix or any advice Thanks,Taylor