1972 Duster, 340/4, black on black (the endgame)

Is that 4-speed you have a OD unit?
I have both but the OD is going in it. My daily commute is 24 miles down I90 at 80 MPH so anything I can do to make it easier will help. The standard 4 speed can go in when I feel the need to play. The bellhousing is opened up about 3/32" to fit the smaller bearing retainer I picked up for it so it's all good.