Welcome to the forum,
As far as I know all taillights fit all years for the cruiser. You might have to do a little wiring or use a bulb holder from one light to the other but all lights fit into the recess. The only lights that need a little bit more work than most are the Rocket tail lights.
As far as where to get them, eBay usually has a set or 2 for auction and here's a couple of sites to look at:
TailLightCovers
Exterior: Race and Street