I have a Besson Sovereign 981 Eb tuba which was made in 1991.
I used to play a 982 regularly and this was made in 1989.
Looks like 'globe' Sovereigns were made in the 70's & 80's but definately not in the 90's.
The best way to check out the true age of a B&H/Besson instrument is by the serial number.
Click on this link to the Besson website to do this;
http://www.musicgroup.com/Instruments/service/FrameSerialnumbers.htm
Advertisers on Ebay don't often disclose serial numbers but there is no harm in asking for it and then doing the search.