Not a successor
Pablo Hidalgo said on Twitter that it's not a successor to the 616, just a different model in concurrent use (https://twitter.com/pablohidalgo/status/772564015469834240). Which makes a lot more sense, since the 74-Z was in RoTS. ZeldaTheSwordsman (talk) 23:28, September 4, 2016 (UTC)
It is an Imperial bike
From DataBank on Speeder Bikes in general it says about the 74-Z specifically: "One of the best-known speeder bikes is the Aratech 74-Z, which saw service during the Clone Wars and remained a mainstay of Imperial forces during the Galactic Civil War." Eddo36 (talk) 03:41, March 20, 2017 (UTC)
Lenght
Star Wars: Geektionary: The Galaxy from A - Z (p. 7) tells that 74-Z speeder bike is 3.2 metres long whereas Star Wars Encyclopedia of Starfighters and Other Vehicles tells it's 3.3 metres long. What should we do about this? East6 (talk) 04:57, 31 May 2021 (UTC)