For the 1999 Subaru Impreza, the low-beam and high-beam headlights both use a 9003 bulb. The supplied fitment data does not identify a separate projector or non-projector headlight variation, so verify the original bulb and connector before ordering.
Front fog lights may use either H3 or H3C. Front turn signal fitment varies among 1156, 194, and 7441 bulbs, while the rear turn signal and reverse light use 1156. Brake and tail lights use 1157R.
For the center stop light, compare the original bulb: the options listed are 921 and 912. License plate and parking lights may use 194 or 7441. The front side marker uses 194NA, and the rear side marker uses 1157A. Interior fitment also varies: compare the original bulb for the ash, dome, and instrument lights. Map lighting uses DE3175, while the trunk light uses 168 or 917.