I have a 2002 Envoy (rwd) SLT and I do know for a fact that the rear diff CAN lock. But, just out of curiosity, I was wondering how to tell if what type of differential the SLT trim has. Something that is pretty odd is that when I look up the VIN on a VIN checker website it tells me it's an SLE, though the car has the side decal reading SLT. I'm assuming the differential is trim specific or I could find out by looking at the VIN. Thanks in advance for the help!