BE COPO rears ?

[beater68427]

This is the rear in my 6cyl car, car had been parked since 73-4 but I have been told it's fake, and the date is early. I didnt know what a BE was till I joined this site after asking a question about the rear so then I started checking into the BE's mine did not have the 4:10's in it but GM 1970 4:88 gears. The powers above say they are a COPO only rear but I still believe they could have been purchased over the counter I know there are gears out there with dates as early as 67.