For the 2001 Chevrolet Silverado 1500, the low-beam headlight uses a 9006 bulb, while the high beam uses a 9005. The fog light fitment is 880. No projector or non-projector headlight variation is specified in the supplied fitment data, so compare the existing bulb and housing before ordering if your truck has a different headlamp setup.
Other exterior bulbs include 3157A for the front turn signal, parking light, and rear turn signal. The tail light and brake light use 3157R, while the reverse light uses 3156. The center stop light takes a 921, and the daytime running light uses 4114. Front and rear side markers are listed as 194NA and PC195NA, respectively.
Several interior and utility locations have options that should be matched to the original bulb. The license plate light is listed as 97 or 194; courtesy lighting may use 1003, 2721, or 211-2; and the engine compartment light may use 93 or 89. Compare these bulbs before replacement.