1977 Greco Les Paul - Anyone know the model number ?

Hii there, Im selling my beautiful and near mint 1977 Greco Les Paul Black Beauty. People keep asking me the model number and Ive narrowed it down to an ES 450 or AN ES 500 but Im really not sure. Any ideas?? The serial number corresponds to a 1977 Greco. Any further information would be appreciated. By the way its a killer guitar and I ate it as 95 percent of my 68 Gibson Les Paul...i may be subjective thou!