I think you need to contact the records center in St. Louis. SF 180 is the form you need, if my memory is correct. You can link to the Personnel Center in St. Louis from a number of military and vets' sites.
When I got out, they told me and my husband to have ours recorded and copied in our local county hall of records. We did.
I'm sure we've all heard about the fire that burned many of the old records...this was the insurance we were advised to get.