Hey,

I thought I'd give a list of all the light bulb sizes for the different lights on the blazer. I know these sizes will definitely fit the 95-97 blazers and should fit the newer blazers as well but not completely sure on that. I know I'm in the process of changing the interior lights on the blazer to led's. And I just wanted to help anybody that doesn't know what size goes where. So here is the list.

Ash tray [161]
Automatic transmission indicator [PC74]
Back up light [1156]
Back up light [3156]
Brake warning [PC74]
Check engine indicator [PC74]
Directional signal indicator [194]
Directional signal indicator [PC74]
Front sidemarker [194]
Front turn signal [3157A]
Glove box [1003]
Glove box [194]
Hi-beam indicator [PC74]
Instrument-general [161]
Instrument-general [37]
Instrument-general [PC168]
Instrument-general [PC74]
License plate [194]
Map light [194]
Parking light [3157A]
Rear turn signal [3057]
Seat belt indicator [PC194]
Step/Courtesy light [1003]
Step/Courtesy light [211-2]
Step/Courtesy light [7065]
Stop light [3057]
Tail light [3057]
Trunk/Cargo area [211-2]
Under hood light [93]

Footwell and gauges with tach, oil, gas, volt, and temp are also a [194]

 

Sylvania's Lamp Replacement Guide gives a good rundown as well.