That is one of the reasons I was looking to see if I could find out when if ever the 5000 phone number was associated with the Thunderbird. That one matchbook cover is the only one with that 5000 #. I have lots of early Thunderbird paper and none use the 5000 phone number , as all use the 5100 #. My next quest ( since you found the 5000 # being used in March 1949 by Nevada Bank) would be to see if Nevada Bank was using that 5000 # in 1948. If that 5000 # is being used by the Nevada Bank in 1948 then the logical explanation would be an error by the match manufacture or an error from Thunderbird representative who gave match manufacture wrong info to print up matches. Thanks again for all your help.