The MOOG #5660 is an all around favorite spring. However, many guys end up cutting a 1/2- 1 coil out of it depending how much lower you want the car to sit.
Monte Carlo's tend to sit high with stock springs which are more than likely the F-41 variety.
The #5658 will probably lower the car a slight bit being less stiff than the 5660.
Here's a MOOG spring chart that's posted on Maliburacing.com : Hope this helps you.
http://www.maliburacing.com/coilspring.htm
Jack
Monte Carlo's tend to sit high with stock springs which are more than likely the F-41 variety.
The #5658 will probably lower the car a slight bit being less stiff than the 5660.
Here's a MOOG spring chart that's posted on Maliburacing.com : Hope this helps you.
http://www.maliburacing.com/coilspring.htm
Jack