*SetBody() - symmetric body pair
Sets the mass properties of a symmetric body pair.
Syntax
*SetBody(body_name,LEFT|RIGHT, mass, 
                                         ixx, iyy, izz, 
                                         ixy, ixz, iyz)
    Arguments
- body_name
 - The variable name of an existing body pair.
 - LEFT RIGHT
 - If LEFT is specified, the properties are assigned to the left body, and the right body properties are made symmetric to the left body.
 - mass
 - The mass of the specified side of the body pair.
 - ixx, iyy, izz, ixy, ixz, iyz
 - The moments of inertia of the specified side of the body pair.
 
Example
*Body(crank, 
"Crank", 
crank_cm)
*SetBody(crank, 
LEFT, 
3, 
10000, 
10000, 
10000, 
0, 
0, 
0)