To find the gear ratio for *your* specific Suburban, you need to:
1. Check the sticker on the driver's side doorjamb: This sticker lists some vehicle specifications, and *might* include the axle ratio. However, it's not always included.
2. Look for a tag on the differential: This is the most reliable method. The differential is located in the rear axle. You'll need to get under the vehicle to locate the tag. The tag will usually state the ratio (e.g., 3.42, 3.73, 4.10).
3. Check your owner's manual (if you have it): It might list the axle ratio, but again, it's not guaranteed.
Without knowing the specific options on your truck, it's impossible to provide a definitive answer. Common ratios for that year and model ranged from approximately 3.07 to 4.10.