The Tech Level Stages chart on p.497 shows both Ultimate (an extension of Advanced) and Obsolete (an extension of generic).
The Tech level Stage Effects chart below does not show obsolete.
Gun Maker mentions Ultimate on p.209, p.213 & p.217 but only shows Obsolete value on p.221.
Armor maker mentions Ultimate on p.228 but only shows Obsolete values on the charts on p. 233 and p.236.
Ultimate and Obsolete are not the same anymore than Generic and Modified are the same.
I would like to see values for obsolete added to the Effects chart on p.497 and values for Ultimate added to the Makers where needed, especially p.233 and p.236
You pose an interesting question. First, what is needed is some sort of definition as to what "Obsolete" means. Does it mean that it is from a much lower Tech Level? Does it mean that it is no longer in common use? Does it mean that it is no longer a useable object or piece of equipment?
A Long Bow or Crossbow are defined as "Obsolete" in terms of military usage, but if you need to take out a sentry quietly at 20 or so yards, they do a very nice job. The Crossbow is illegal for hunting in Illinois because it is silent, but very easy for the average person to use, making it highly suitable for poaching. The bow is a Tech Level "0" weapon, while the Crossbow is probably around Tech Level 1.6.
Papyrus rafts were being used on the Nile River and some of the lakes in Africa before 3500BC, or Tech Level "0". Does that make them "Obsolete" and no longer fit for use in the present day?
Steam Road Locomotives and Traction Engines began to come into wide use beginning in the 1850s, so Tech Level 3.6. Does that make them "Obsolete" and no longer useable in the present?
Horse-drawn vehicles date as early as 3500BC or Tech Level 1, and I would argue that they were around earlier. Does that make them "Obsolete"? Note, those individuals driving in the Arcola area of Illinois, near Shipshewana in Indiana, and the Lancaster and York areas of Pennsylvania do need to watch out for the Mennonite and Amish horse-powered vehicles on the roads.
Rope made from vegetable fibers, such as papyrus and hemp, has been around since Tech Level "0". Is vegetable fiber rope "Obsolete"?
Edit Note: The Alaskan Eskimos that are taking Bowhead Whales on the Alaskan North Coast were in the 1980s still using Bomb Guns and Bomb-Lance equipment from the 1860s. Obsolete?