Where did you look this up, Kevin?
I see the Stovebolt "VIN" buster does not recognize that KBA preface.
Maybe it works with the Vehicle Serial Number?
Is there a Vehicle Serial Number plate on the driver's side door jamb?
KBA is the Engine Serial Number preface for a 1952 Chevrolet 3100 truck assembled in Flint, MI
http://www.1954advance-design.com/chev-specs/1952-Chevrolet-t-ser.jpgThe 1951 3/4 ton Engine Serial Number preface is not that code.
http://www.1954advance-design.com/chev-specs/1951-Chevrolet-t-ser.jpg