Rear brake rotor differences

I found out why my axle was dragging. I was trying to replace the rotor on the left with the one on the right. Ron Ayers has both listed. What do I need to do to get the one on the right to fit. Is the spacer only used for the left one?

Left rotor part 43251-MBG-000

right 43251_MBG-E01

 

Spacer is only for the '98-'99 VFR800. Fits in the recess of the first rotor. No spacer after 2000.