01'-02' taillights in a 98'?
 

Will they fit, or is work required?

Yes, they will. My little brother (98_3RZ) has '04 tail lights on his '00.

It's a bolt on but the wiring is slightly different. You will need to re-pin the 01-02 taillight to match the 98. The wires are the exact same as far as colors go, you just need to move a couple to different slots in the taillight harness. Very easy to do, you just need a very small sloted screw driver to depress the metal tab and the wire will pull out.