hi Jerry
yes, it is a NS64 shell. i have another one too.
a reissue m35 dd ( NS 66 ). this helmet was weared by a "heeres offizier". this "heeres offizier" was "offizier der reserve | luftwaffe" too ( brown "luftwaffen" chinstrap ).
and here some other heers
m35 reissue (Q66)
m42 sd reissue (ET68)
kind regards
Basti