When doing replacement or upgrading on 1997 – 2001 Cadillac Catera capsule halogen headlamps HID with, the bulb size guide is necessary for you to take the reference.
Jump to corresponding car model with the catalog bellow.

Low Beam Headlight1997 – 1999 H7
High Beam Headlight1997 – 1999 H7
Front Fog Light1997 – 1999 H3-55W
Back Up Light1997 – 1999 1156
Brake1997 – 1999 1157
Dome Light1997 – 1999 578
Front Side Marker1997 – 1999 194
Front Turn Signal1997 – 1999 3457
License Plate1997 – 1999 12844
Parking Light1997 – 1999 3457
Rear Side Marker1997 – 1999 194
Rear Turn Signal1997 – 1999 PY21W
Tail Light1997 – 1999 1157
Courtesy1997 – 1999 6411
Glove Box1997 – 1999 578
Map Light1997 – 1999 168
Low Beam Headlight2000 – 2001 H7
High Beam Headlight2000 – 2001 H7
Front Fog Light2000 – 2001 H3-55W
Back Up Light2000 – 2001 1156
Brake2000 – 2001 1157
Dome Light2000 – 2001 578
Front Side Marker2000 – 2001 194
Front Turn Signal2000 – 2001 3457
License Plate2000 – 2001 12844
Parking Light2000 – 2001 3457
Rear Side Marker2000 – 2001 194
Rear Turn Signal2000 – 2001 PY21W
Tail Light2000 – 2001 1157
Courtesy2000 – 2001 6411
Glove Box2000 – 2001 578
Map Light2000 – 2001 168
Low Beam Headlight2000 – 2001 D2S
High Beam Headlight2000 – 2001 H7
Front Fog Light2000 – 2001 H3-55W
Back Up Light2000 – 2001 1156
Brake2000 – 2001 1157
Dome Light2000 – 2001 6411
Front Side Marker2000 – 2001 194
Front Turn Signal2000 – 2001 3457
License Plate2000 – 2001 12844
Parking Light2000 – 2001 3457NA
Rear Side Marker2000 – 2001 194
Rear Turn Signal2000 – 2001 PY21W
Tail Light2000 – 2001 1157
Courtesy2000 – 2001 6411
Glove Box2000 – 2001 578
Map Light2000 – 2001 168