John the ebay ad wording
this is an upgraded** Eminent Technology ET2.5 Air Bearing Tonearm
implies to me that it is an original ET 2.0, whose manifold and spindle were sent to Bruce. An ET 2.5 Manifold and Spindle returned to the previous owner. This can also explain why there are two aluminum arm wands. All other parts I Beam, Arm Plate Mount / VTA Block, Joint (Gooseneck) are shared between the two versions.
It is rare to find a 2.5 manfiold/spindle for sale in auctions. If I were building from used purchases a 2.5, or for that matter even the 2.0; I would still be ordering from Bruce the upgraded aluminum gooseneck (joint), mounting plate ......and the long beam :^)
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the Ebay ad wording of "upgraded" is also misleading. If one plays MM cartridges the 2.0 is the better choice. All depends on which the listener prefers.
If I recall buried in this thread somewhere, there are close to 3000 ET tonearms out there. How many would there have been if the ET 2.0 tonearm was not introduced the same year as the perfect sound (cd). 8^0