Hello Jerr, To check the Head gasket for your Sierra and the fitment please use our Vehicle Selector — which can be found towards the top of the homepage as well as all category, search results, and product pages — can help verify if a part will fit your specific application. To enter your application, simply select your vehicle’s year, make, model, sub-model, and engine type and click “Go.” Once your application is selected, you’ll see a “Guaranteed to Fit” badge if the part will fit, and we recommend that you also double-check Your Vehicle Fit Details as well as the Vehicle Fitment Information table on the product page.