What year did Epiphone owners stop putting Gibson replacement truss rod covers on? =P
Most actual Gibson truss rod covers don't fit Epis. I bought an Epi Firebird that was missing the truss rod cover and found an old Gibson one and it didn't line up with the Epi screw holes so I couldn't use it. I ended up making on of my own but it's missing the Gibson name. Gibson LP Truss rod covers have only 2 srcews Epis have three, a lot of the Epi truss rod covers were made slightly different than Gibson so people couldn't swap them with out a buyer noticing. Epi truss rod covers for the longest time said GIBSON on them up until recently. I am not sure when they actually stopped but most of the Epis I have bought all had Gibson truss rod covers on them.
a bad guess on my part lol must've sounded like a smartass...

well I hope someone has an answer for u, it's an interesting question
A lot of people think people put Gibson truss rod covers on Epis. The worse thing is when you go to buy a Gibson LP and someone put the Epi Gibson truss rod cover on it so if you want to put an original on it you see the two srcew holes. A lot of Gibson counterfits have the wrong truss rod cover (Epi Style) on them the first clue is not a real LP. I can email a friend at Gibson and see what he has to say.