is this a real of fake killer bee on ebay?

Having an unanodized case and normal short needle valve, that is an Estes era Killer Bee. Likely having a normal (non lightened) bee crankshaft. It does appear to have the proper slit cylinder with sub-piston induction.

The Estes era Killer Bees can be found with both silver and gold cases, and almost always have a normal black cap needle valve (but be careful as one can easily swap the needle valve and make it look like an earlier one). Most if not all have the proper slit cylinder. Some have reported that the very last Killer Bees from Estes used a basic Sure Start cylinder (with no sub-piston induction), although I cannot say I've seen a legitimate one like that in it's original package. An engine like that would be no different than a Sure Start with a zero drag driveplate. I'd expect only the pre-Estes Killer Bees to have the proper lightened piston and tapered grind.