Hey Jim,
until now, Onefinity never called the Y axes “Y-35” or “Y-50”, but it’s me who does that because it is logical 
| Model | X axis | Y axis | |
|---|---|---|---|
| Machinist | 16" X-35 | × | 16" Y-35 |
| Woodworker | 32" X-35 | × | 32" Y-35 |
| Woodworker X-50 | 32" X-50 | × | 32" Y-35 |
| Journeyman | 48" X-50 | × | 32" Y-35 |
| Foreman | 48" X-50 | × | 48" Y-50 |
Left: Rail with 50 mm ø chrome-plated steel hollow shafts
Right: Rail with 35 mm ø chrome-plated steel hollow shafts
The photo was obviously made when there was a “Woodworker” and a “Woodworker X-50” version, but it shows the two sizes of Onefinity modular rails system.