What I mean to say is the following
The counterpart of the 2SK146 is the 2SJ73,
there the drain`s are diagonally opposite each other, that happens because they are the same Fets in a housing.
The 2SK146, on the other hand, has the drains facing each other, which is only possible if two different felts are used, so the manufacturer would have made two different versions of the 2SK146 so that the drains would be opposite each other.
Hope I have displayed it that well.