Well, that's kind of a trick question. The warning indicator bulbs are T5 style wedge bulbs, but the contacts are spot welded directly to the bulb, so you can't just replace the bulb. The twist locks are somewhat unique since the keyways are so narrow.
You'll also need to be sure that you get the polarity correct or you'll never know when a warning indicator comes on.
If you just want to replace the gauge cluster backlighting,
www.sportscarleds.com has kits for pre-facelift clusters (this is what I used).
These may work for the warning indicators and the 3 LCDs on '97-2000 pre-facelift clusters without the larger center LCD display, like mine pictured below. The problem is the lock keyway is large, while ours are small.
http://www.ebay.com/itm/10-Twist-Lock-2-2835-SMD-T5-Instrument-Cluster-Indicator-Led-Bulbs-White-Light-/261968318158
The rotary gauges take 2 x T5's and 2 x T10's.
T10's that fit the rotary gauges.
http://www.ebay.com/itm/3X-T10-White-LED-Bulbs-with-Twist-Lock-Holders-Instrument-Gauge-Cluster-Lamp-/171904729813
May need to trim the keys on new twist locks to fit into our narrow keyways.
