Shaft is Planet Eclipse's barrel they produce (Like Dye's Ultralite/Boomstick, Smart Part's Freak, etc...). They have produced the Shaft Solo, Shaft 2, 3, and 4. Also with SL (Shaft 2,3,4 milled differently for the SL Egos) variations for each model. Also since after the Etek 2 they have made "simplified" Shaft 3, and 4 barrels for the Etek 3/4 and Etha. The reason I say after the Etek 2 was in my opinion the Etek 2's stock Shaft 2 was the same as the 08 Ego's Shaft barrel. After that they simplified the milling and porting but retained the exact same threading (where the two barrels join) as the Shafts that came with the Egos. Hope this answers your question.
Planet Eclipse Etek
w/. Star frame, 08 Ego expansion board, Etek 2 regulator, Ego10 OOPS ASA, SLS Cure 3+ bolt w/. inserts, Zick kit, Kila detents, Violent thumbwheel, PE red laser eyes, Shaft 4 barrel kit w/. all backs and fronts, both Bump pistons.
V3 Dye Rotor w/. Virtue board
114/4500 Carleton w/. Myth reg
Ego/Etek Parts FS/T