Not sure about the date, but I think the LeGrande II's and III's came out together. As I recall, it was kinda like an after the fact nomenclature type of thing.

When Ron Sr first developed his all-pull PSG back in the 80's, they were called the LeGrande. But a short time thereafter they were called Lashley LeGrandes.

There is so little diference between the later Lashley LeGrande and the LeGrande II that it is hardly worth mentioning. The big difference came when Ron developed the counterforce ass'y to get around cabinet drop. All guitars shipped with this mod, are III's.

So I believe to distinguish between the Lashley LeGrande and the ones with the counterforce, they added the II and the III after the word LeGrande and simply dropped the term Lashley LeGrande. IE, II's do not have the counterforce mod, and the III's do.

There are basically 5 LeGrandes out there:

1. The original LeGrande. It was a shorter guitar with a short keyhead and a changer supported between each finger.

2. Lashley LeGrande with 4 hole bellcranks. This is a regular sized LeGrande with regular sized keyhead and changer; as used to day.

3. Lashley LeGrande with 14 hole bellcranks.

4. LeGrande II without the counterforce mod on either neck.

5. LeGrande III with the mod on either or both necks.

I am sorry I do not know the dates each of these was introduced.