Carol, Oklahoma became a state in 1907. There was no official vital records registration before that date.

As for Grand Army of the Republic (G.A.R.) records, you might check with the Oklahoma Historical Society in Oklahoma City.
http://www.electriccemetery.com/ecOKGAR.html

The records of Garfield Post #65 of McLoud, Oklahoma are extant, consisting mostly of meeting and encampment proceedings. Your ancestor may be mentioned, but there will be little or no personal information about the individual members.

If he served in the Union Army, your best source for personal information will be a pension file, which is available for a fee from the National Archives. http://www.cyndislist.com/cyndi/pensions.htm

I wish you the best of luck in your quest!

Terri Walker
Rachel Cormany No. 2 ASUVCW
http://rachelcormany-asuvcw.moonfruit.com