I recently bought this 98xlt 4x4. I KNOW it has a 3.55 non locking 9.75 rear differential because I replaced the rear pinion bearings. But when I lock it in 4x4 and I'm turning on dirt or gravel the rear tires act as if it's a locking differential or has a spool or solid axle ! How and why is this possible ?

 

What does it say on the tag? Unless you disassembled the diff you may not can tell if it has traction lock. Just looking at it with the cover off, you can't see the clutches.

 

Yes I disassembled the entire differential to replace the pinion bearings. It's just a open differential. I have another 97 4x4 that's a lariat and the tag on it's differential has a L on it to indicate locking. I don't understand , the 98 just has the spider gears and they haven't been altered.