[Baker]

All 88-91's will bolt up perfectly and fit.
88/89 have a different style than 90/91's. 90/91 has a dark red trim around them with a different center light as well.
Whichver tail lights you get, retain your stock(88/89) bulb harness. The 90-91 bulb harness does not plug into the 88/89 car.

You can find info and see differences here...

http://crxcommunity.com/viewtopic.php?t=6216

 

[Baker]

Np...these may be better pics...

88/89 Tail lights

90/91 Tail lights