John,
The IL Adjutant General's Report has him being transferred to the Veteran Reserve Corp, but the date of the transfer isn't listed. He may have been sent to Nashville (or somewhere else) for guard duty, etc. The transfer means that he wasn't well enough to perform his normal duties.

I don't have a pension file for him, but I have a roll of microfilm for Co G. I haven't read it yet to see what's on the film. Also, I have some files for other men who served with him. I'll look and see if he's mentioned, as they often mentioned men who were hospitalized with them.

He didn't by any chance have a widow named Mary who was living in Brownsville, TN in 1873 did he? I have a letter she wrote, but she neglects to mention her late husband's name.

I agree with Alan Pitts. Rather than ordering a pension file from the National Archives yourself, it's best to have a reputable researcher do this. You'll likely get better results, and they are always much quicker.
Ann