The 1998 GMC Suburban V8 firing order depends on which engine it has. GM used several V8s in that year. You must identify your engine's displacement (e.g., 5.7L, 7.4L) to determine the correct firing order.
Once you know the engine displacement, you can find the firing order in your owner's manual or online through a reliable automotive resource. Searching "[Your Engine Displacement] firing order" will likely yield the correct information.
