Click on this link for SSDI:http://ssdi.genealogy.rootsweb.com/cgi-bin/ssdi.cgi
Type in last name of Marsh, first name of Bascom, click on Submit.
To the far right of his name, in blue letters, see SS-5 Letter? Click on that and up will come a letter all ready to print out. You sign it and give your mailing address, too. Enclose fee they request.
Happy Hunting (^_^)