If its the 1980, does it still have the mechanical adjust for shift points? If that got knocked loose, it could be keeping it from shifting. I havent seen a 240D past 1980 so I cant help if its the 83.
When I replaced the trans in my 240D and learned to adjust the shift points, my first try was way off, it was in 4th gear at 18 mph... and I was in traffic on a test drive...a little embarrassing...
