His service with 3d Field Artillery ended two years before the war. He apparently re-enlisted at some point later. I can reconstruct his service but I'll have to charge you.
Re his discharge papers. Check with the county clerk of the jurisdiction where he entered service. Some jurisdictions paid a war service bonus and applicants were required to provide discharge/separation papers to establish eligibility. Clerks usually required (or made) copies to keep on file.
Also, over the years, veterans have been required to provide discharge/separation documents to establish eligibility for an increasing number of state and local veterans programs so you might check with authorities in jurisdictions where he's lived since the mid- to late 1960's.