I put in 1998 for your truck... great web site!
http://www.sylvania.com/ConsumerProducts/AutomotiveLighting/LampReplacementGuide/AutoLRG-Results.htm
Auto Lamp Replacement Guide - Results
Print out the list and find them at your nearest retailer.
1998 DODGE Ram Pickup
High & low beam headlamp
9004LL
9004SU Silverstar ULTRA for Ultra Night Vision - The Whitest and Brightest Halogen
9004ST Silverstar High Performance Lighting: The Whiter and Brighter Halogen
9004XV XtraVision Halogen - The Brighter Light
9004CB Cool Blue Halogen - The Whiter Light
Parking light
3157A
3157AST Silverstar Signal Lighting: Complete the Look: Crisp, Clean, Style
3157NALL Long Life Upgrade: Up to twice the life of the standard lamp
Front turn signal
3157A
3157AST Silverstar Signal Lighting: Complete the Look: Crisp, Clean, Style
3157NALL Long Life Upgrade: Up to twice the life of the standard lamp
Rear turn signal
1157
1157LL Long Life Upgrade: Up to twice the life of the standard lamp
3157
3157LL Long Life Upgrade: Up to twice the life of the standard lamp
Tail light
1157
1157LL Long Life Upgrade: Up to twice the life of the standard lamp
3157
3157LL Long Life Upgrade: Up to twice the life of the standard lamp
Stop light
1157
1157LL Long Life Upgrade: Up to twice the life of the standard lamp
3157
3157LL Long Life Upgrade: Up to twice the life of the standard lamp
High mount stop light
921
921LL Long Life Upgrade: Up to twice the life of the standard lamp
Fog/Driving light
893
893ST Silverstar High Performance Lighting: The Whiter and Brighter Halogen
License plate
1155
168
168LL Long Life Upgrade: Up to twice the life of the standard lamp
Back up light
1156
1156LL Long Life Upgrade: Up to twice the life of the standard lamp
3157
3157LL Long Life Upgrade: Up to twice the life of the standard lamp
3157
3157LL Long Life Upgrade: Up to twice the life of the standard lamp
Front sidemarker
3157A
3157AST Silverstar Signal Lighting: Complete the Look: Crisp, Clean, Style
3157NALL Long Life Upgrade: Up to twice the life of the standard lamp
Rear sidemarker
194
194LL Long Life Upgrade: Up to twice the life of the standard lamp
Ash tray
161
Glove box
1891
Dome light
579
Step/Courtesy light
194
194LL Long Life Upgrade: Up to twice the life of the standard lamp
Trunk/Cargo area
921
921LL Long Life Upgrade: Up to twice the life of the standard lamp
Under hood light
561
Instrument-general
158
PC194
PC74
Check engine indicator
PC74
Hi-beam indicator
PC194
Seat belt indicator
PC74
Brake warning
PC194
Automatic transmission indicator
PC74
Directional signal indicator
PC194
Ignition switch
1445