Also states and sometimes the their counties have memorials of those who served. Contact the local historical and/or genealogy societies where he lived when he enlisted (he might have enlisted at a different location/county/state). My great grandfather lived in IN and he enlisted (Mustered In) and discharge (Mustered Out) were in IL. Also check with Veterans associations he might have joined in later yrs in the area he lived.
I have seen the birth yrs, census ages, other documents ages be different by 5 yrs so don't lock on one yr of birth.