The FCC have a commercial partnership with Best Copy & Print Inc, who can manually search through the FCC archives on your behalf to retrieve and duplicate old licensing documents. A fee is charged for this service, but it's quite reasonable.

http://www.arrl.org/call-sign-research

If your grandfather's callsign is not in current use, you may be able to apply to use his old call sign through the Vanity Call Signs program.

http://www.arrl.org/vanity-call-signs

thank you! I think I may buy this service much appreciated!