Beech19 From United States of America, joined Jul 2006, 936 posts, RR: 4 Reply 7, posted (7 years 1 month 3 weeks 6 days 21 hours ago) and read 9177 times:
Yes... that is a American Airlines 747-100 (N905NA) that was purchased by NASA to test Enterprise. It was converted in 1976 but kept the AA paint during testing.
They purchased the second one in 1988. It was a 747-100SR (N911NA) taken from JAL and entered service in 1990 after being modified. The AA one was retired and lives at the Pinal Air Park in AZ now. The other beinig the active carrier and lives at Edwards Air Force Base.