My 2014 GMC Sierra was manufactured 8/13 but it's Vin and registration says 2014. I bought it new in January of 2014. When did the body style change, and does it follow the 2013 technical info or the 2014 technical info? It's a 3500 HD Duramax, 4x4 crew cab. Not sure which forum to follow......

 

8/13 is the build date - 2014 is the model year. All manufacturers use both (at least in the USA).

The build date is used by manufacturers for several reasons but most often for tracking which vehicles may be affected by production problems and determining if a recall should be issued (in conjunction with the VIN).

The model year is used for all service and repair information. When ordering any parts or manuals, you should be looking for a 2014.

Additional FYI - the model year can be confirmed by the 10th digit of the VIN - a 2014 should be “E” - and the engine by the 8th digit.

There is also a sticker in the glove box with a bunch of 3 digit codes on it - these are the options your truck is equipped with. The engine code will start with “L” and you can find definitions here -

https://rparts-sites.s3.amazonaws.co...n/rpoCodes.pdf

 

and I believe the bodystyle change for the 2500 3500 happened one year after the 1500