I have this transmission installed in my 1976 Sprint. The shift points are 14mph 1st to 2nd. 26 mph 2nd to 3rd. 40 mph is 3rd to 4th shift. If I slow to 38 mph it will go back to 3rd gear. When I first put in in the Sprint it did not want to go into 4th(overdrive). I took it to the shop I bought the transmission from and the owner pulled the cable out as far as he could three or four times quickly. He said that sometimes the pressure valve hangs up a bit and causes the no overdrive. Anyway after he did that the trans works great.
BTW you can shift it manually and hold it in any of the three gears for as long as you want.