Okay, this is what I measured:
83 KX250 Swingarm (Gold):1. Inside distance between the wheel end = 219mm (outside at wheel end is 240mm)
2. Outside distance at the swing arm pivot end = 192mm
3. Gap between the swing arm pivot bearings = 112mm
4. Length of pivot bearing housings = 40mm
5. Length from swing arm pivot centre to very end of the arm = 625mm
6. Total length = 641mm
84 KX250 Swingarm (silver):1. Inside distance between the wheel end = 203mm (outside at wheel end is 264mm)
2. Outside distance at the swing arm pivot end = 192mm
3. Gap between the swing arm pivot bearings = 112mm
4. Length of pivot bearing housings = 40mm
5. Length from swing arm pivot centre to very end of the arm = 631mm
6. Total length = 648mm
Hope that helps mate,
Hardo