Subject to correction by someone who actually knows, I do not believe the "Classic" and "Excella" nomenclatures were ever used contemporaniously.
The "Excella" name goes back to a period when there were two, or sometimes three levels of trim: Sovereign
, Excella, and (in some years) Limited. This was more or less the mid to late 1980's. In the early 90's there were two choices of trim: "Excella", and "Limited". This continued into the late 90's with the addition of a lighter weight model, available only in certain sizes, called the "Safari". A few years ago the, uhm, classic model was renamed the "Classic", which seems to still be available in a higher price "Limited" version as well.
If you like, you may consider the late model "Excella" and the current "Classic" to be more or less the same.