The first step is to remove the front end from your Slash, as well as the front bumper
Now remove the skid plate. Also remove the two steering post screws and washers
On the upper chassis plate, there is a body post. Cut this off with either a Dremel, or by scoring it with an Xacto knife.
When you put the steering assembly on the Rustler upper chassis, be sure you don’t tighten it so far that it causes binding