Yes, the overdrive gear actually sits in the normal 3rd gear location, and the shift levers are flipped.
Because of that when the transmission is in overdrive there’s more force going back into the shafts (since it’s not a “direct drive” gear), which is why the larger bearing retainer was used. And the rollers between the input and output shafts get more wear because the shafts aren’t locked together by the collars like they normally would be in the 1:1 fourth gear.
A lot of people dog on the strength of the overdrive transmissions. They’re not quite as strong as the standard 833, but they’re still plenty strong enough. And they can be strengthened, you can bush the shafts in the case to improve their strength (or remove shaft play if the case is worn).
