Joe Baugher's web site says the service ceiling should be 35,000 ft.
http://home.att.net/~jbaugher2/b17_16.html Service Ceiling is defined as the altitude where best climb rate drops to 100 fpm.
I took it up with the normal load (100% fuel, 6,000 lb bombs) and it hit 100 fpm at about 33,500 feet.
Not really worth complaining about, but just a fact to note.
[This message has been edited by funked (edited 04-14-2001).]