To be certain:
* Consult your owner's manual: This is the best source for the exact location.
* Look for a low-profile, typically brass or plastic plug: It's usually smaller than other bolts or fittings in that area.
* Refer to a repair manual: A Haynes or Chilton manual specific to your year and model Suburban will have diagrams showing the location.
Important Note: When draining coolant, make sure to do it safely. The coolant is hot when the engine is warm and is also corrosive, so wear gloves and eye protection. Have a suitable container ready to catch the fluid.