The gearbox case for the 56 series gearboxes are interchangeable with each other [3 speed, four speed, four speed close ratio option-one & ultra close ratio option-two]

Additionally, the 56A gearbox cases are also interchangeable with each other. [four speed, five speed & five speed option-one]

With this in mind, it would stand to reason that the gearbox case from the 60 series would very likely also be interchangeable with each other. The main difference with the basic layout of these small Datsun gearboxes was in the number of gears that went into the extention housings

3 speed= all gears inside the case
4 speed= reverse in the extention housing
5 speed= first & reverse in the extention housing [F5W56A] I don't know which gear is out there in the 60 series overdrive models, but it's either first or fifth.

This means that the extention housing is different for each one & I wouldn't be surprised if they were different between the 60 series dogleg & regular shift versions too.