does the z-71 have heavier duty parts??I am asking this question because i have a white 1994 gmc ext cab 4x4 and my freind has a 1994 white ext cab z-71 and they are the exact same truck!! except for the grill and his says z-71 and mine says 4x4.I am pretty sure chevrolet started z-71 in 1989 but i am beginning to think gmc didn\'t start using it until 1995 or 1996 because i have never seen a pre 1995 gmc using the z-71 badge.Z71 RPO started in 88 (as said above)The package has changed slightly over the yearsUsually includes different (stiffer) valved shocksFront differential skid plate, transfercase skid plate, sometimes a fuel tank skid plateThat usually itThe spring rates can be the same for a Z71 vs a non Z71The rear locker G80 RPO is not included in the Z71 package, it is an option with or without the Z71My \'97 is a Z71 has a crappy aluminum front diff and xfer-case skid platesBilstien shocks (not sure if they were factory) and a plastic cover on the fuel tankOper diff rearendMy friend had a \'92 Z71 and had the same stuff as meHe now has an \'01, just incudes skid plates.Other related question