At first glance, these two 1973 TX650 right side covers appear to be identical -- but they are not...
The top cover stands "farther off" from the frame than the lower cover, due to extended tabs (top), and an extended arm (bottom)...
The rubber "carb damper" is also longer...
And, there is an added crescent of sheet metal to hide the gap that all of the extended stand-offs create.
Finally, the mounting bolt is longer on the extended version.
I believe that the extended side cover was a mid-year change. I am not sure, but I believe that only the right-side cover was extended. My speculation is that one of the components that gets attached to the right-side of the battery box must have grown in size, necessitating more room under the cover.
This is a 1972 battery box. You can see that 1972 already has the safety relay and regulator, and they never got bigger. So, maybe the mid-year 1973 right side cover was extended for some other reason? Thoughts?