Studebaker engines were used in the 57-58 Packards...and so marked as 
Packard engines. We will need the numbers off the engine to tell exactly 
what it is: On the top of the engine - front right corner(as you face 
the car)- just in front of the lifter valley cover- to the left of the 
oil stem- will be a small machined pad with a serial number stamped on 
it. If it is the "original" engine, the numbers are shown below:
   Engine number starting at V534901and ascending 
    -259 cubic inch V-8 Engine number starting at P79801 and ascending
    -289 cubic inch V-8 Engine number starting at VC19601 " " 
    -Canada built 259 V-8 Engine number starting at PC2801 " " 
    -Canada built 289 V-8 
  
A Studebaker engine transplanted from a 57-58 Packard will have a 
number beginning with an "L" or "LS"