A raptor is a model 13 with extra braces around the valve box,
The raptor has a different connecting rod, stronger and doesnt have the two piece dipper/rod cap
The raptor also has a stronger, different shaped piston.
There was no governor hole on the raptor.
The carb was also different, it lacked a Choke,
http://www.briggsracing.com/images/lightbox/raptor/img-01.jpg
All engines made after the RAPTOR 3 went into production (all briggs engines) blocks had the casting changes,
Ill look for the pictures,
Edit, Cant find the valve brace pictures =(
See if the motor is worn, if it runs, what it was ran on, and the cost!