The GMC 305 cubic inch engine is a
V6, not a V8. There isn't a widely known "GMC 305 V6" engine. GMC used various V6 engines in different years and models, but not one specifically designated as a "305." The 305 cubic inch designation is typically associated with Chevrolet small-block V8s.
To find the firing order, you need to specify the exact engine code (usually found on a sticker on the engine or in your owner's manual) or provide the year and model of your GMC truck or vehicle. This will allow for accurate determination of the firing order.
