The sensor equipment was .25 and .55 tons. No rules.
With fractional accounting removed as a standard rule, TR3039 made a lot of changes to vehicles, including removing the random sensor equipment with fractional tonnages.
It wasn't that the drones were specifically nerfed, it was fractional accounting that was removed, and the no rules equipment was removed rather than slowing the unit or removing armor. (Warrior going from 10/15 to 9/14 becuase control equipment went from 1.05 to 1.5).
Correction: The Drones were overhauled to be support vehicles. Possilby because without fractional accounting they didn't work at all, but I'm just guessing there. But the old Napfind had .75 for engine, .1 for control, .2 for left equipment, .2 for internal.