The way most set that up is so it disengages LU-OD or both when the vacuum gets low enough from more throttle.
Just a little FYI:
OD can only engage once the trans is in 3rd gear since 3rd gear fluid pressure is what engages OD.
Also note that if you are driving along in OD and lockup and manually downshift to 2nd,,,ZIIING!!!
You will be dropping lockup, OD and 3rd all at the same time, so don’t do that.
I would also be curious as to how the OD and LU shifts are made on yours.
Thanks