Is there a compiled list of Hilton codes, like the Marriott thread?
Here is what I got trolling through this thread
N9880578
for US
Hilton, Conrad, Hilton Garden Inn and Waldorf=Astoria Collection
0560054725
for US
Doubletree, Homewood Suites, Hampton Inns and Embassy Suites
D332376164
for outside
Hilton and Doubletree Hotels
Fedex (10% system wide) N0001231
IBM code, 001368083
N0041604 some, but not all Hiltons
0560041604 Doubletree,Hampton,Embassey