In the 1985 Japanese catalogue there are no Sessions but they are launched in the Winter 1985 Newcomers catalogue.
They are the 503, the 512, and the 520. All Sessions these models don't last long before they are replaced by the
various Session ii models
| Model | 503 | 512 | 520 |
| Release Price | 60,000 Yen | 60,000 Yen | 60,000 Yen |
| Body to Neck | Bolt on | Bolt on | Bolt on |
| Fretboard | Rosewood | Rosewood | Rosewood |
| Frets | 22 | 22 | 22 |
| Body | Basewood | Basewood | Basewood |
| Neck | Nato | Nato | Nato |
| Hardware | Chrome but see note below | Chrome | Chrome |
| Bridge | Rockin Magic 11 | Rockin Magic 11 | Rockin Magic 11 |
| Pickups | SSS | SSH | HH |
| Pickup Switch | 5 way selector | 5 way selector | 3 way selector |
| Control | 1 Vol 1 Tone | 1 Vol 1 Tone | 1 Vol 1 Tone |
| Colours | Black, Pearl White, Candy Apple Red or Blueburst | As 503 | As 503 |
| Scale and Radius | 648mm 350mm | As 503 | As 503 |
I have seen two 503s with gold hardware both in blue burst but the catalogues and archives specify chrome.
I don't think that the two I saw have had the hardware changed
