The most noticeable difference will be the move from 16" rims to 17" rims, with P245/70R17-108S tires now being standard equipment:
P245/70R17-108S all-season blackwall tires standard on 2WD models.
There is also a new rear axle ratio:
3.23 rear axle ratio standard on 2WD models. (GU5)
My guess is that the 3.42 (GU6) went the way of the 3.08 (GU4) and is no longer offered on the Silverado. If this is the case, the next step up in rear axle ratios will be the 3.73 I (GT4).
A more powerful 5.3L motor is also new for 2005:
Higher output Vortec 5300 5.3L V-8 with 310 hp is available on 4WD Extended Cab w/standard box.
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