G-80 and Z-71

In my 2000 Z-71 5.3 L, my gear code of GT5 gives me gears of 4.10 and thats fine. I thought the comment was made around here that G80, the code for rear locking diff (I think) wasn't until 2003, yet I have it on my data plate in my glove compartment... any explanations??

The G80 wasn't standard equipment with the Z71 until then. On the 2002
Z71 I had, it was a $495 option and the 4.10 (GT5) was $50 option.

The G80 wasn't standard equipment with the Z71 until then. On the 2002
Z71 I had, it was a $495 option and the 4.10 (GT5) was $50 option.

Why wouldn't the prior years (Z71) have the G80? Z71 is a 4WD, and the G80 is the limited slip standard for 4WD's. My 1998 Z71 had a G80.

The Older body style might have had them as standard equipment. My 2002 the G80 was an option (with or without Z71 RPO)and my 05 it is included with the Z71 package. GM packages and options are confusing. I was also looking the the "new" Avalanche in 2002 and the Z71 package included the G80, but the 1500 Trucks didn't. Go figure????
Oh, The G80 is actually a locker, not a limited slip. Both axles receive equal torque when engaged.

Oh, The G80 is actually a locker, not a limited slip. Both axles receive equal torque when engaged.

Okay, my bad. Everywhere I've read said Limited SLip...