A270815245
A = a variance from standard specs for cylinder bore and/or bearing grinds/specs
270 = 270 ci GMC engine
815255 = sequence/serial number
Specific details on coding are shown on RobEnglish's oldgmctrucks.com website.
As posted by 3B, many GM vehicles were titled by using that engine serial number for vehicle registration (ID) code. (For some inexplicable reason).
