Not sure about Liberty but there were 11,891 FLHs built in 76.
(special editions are not listed separate)
Try contacting the Graceland Museum. It seems that Elvis had one (or more) of these and they have it on display. They may know production number.
Are you sure it is a Liberty and not a Liberator (seems Elvis had one of these too) both were made in 76. The Liberator was a FLH with a frame mounted fairing w/ two headlites. Don't know if the made a Liberty Liberator though.