Both 1st 2nd and 3rd 4th arms face down on the case on an overdrive. You have one up and one down. At least both of the ones we have are set up this way. But we have only ever ran real 4 speeds so not completely sure.
The reason only 3/4 is reversed is that the transmission has been re-geared so that "the regular" 3rd gear is now the OD gear. So when you shift it, 123, "3" is actually the old 4th gear "straight through" position, and "4" is the old 3rd gear, now the new OD gear
