SW20 Taillights

Unusual mod, and not that straightforward.
 
Your current center garnish won't fit so you would need the early one to go with the lights, and you may need to drill extra holes in the bulkhead to mount it.
 
As Carmikey says you would need the early model lock along with it's operating mechanism because your later one won't work. However you may be able to get a locksmith to fit the tumblers from your later model lock so you can use the same key.
You may also have trouble with the clips that hold the lights. IIRC they are slightly different.
 
You would also need to modify the wiring to work because IIRC the early model connecting plugs are reversed so you would have to cut your existing ones off and re splice in the early plugs.
 
Do you still want to do it?