2011 Siverado 5.3, GAS MILEAGE
#11
TECH Resident
Join Date: Dec 2006
Location: Enid, OK
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It really shouldn't make much more than 1-2 mpg difference if that. When in 2wd you are only spinning the CV axles and spider gears on the front diff due to the left CVs fixed engagement in the spider gears. The carrier itself should stay put unless its a 99 or 00 where the front shaft turned all the time. The 2002s seemed to be the cream of the crop for the NBS. Right out of the box those 5.3 T motors ran strong and got great mileage for a full sized truck. My 99 all stock was an absolute sloth compared to my dads 02 of the exact same specs and even with 2000+ pounds in the bed his still ran better than mine.