Thans for all the comments. This is what I have found out about the transmission, (Linkage lockout removed starting with 1991 Model Year to allow 3rd Reverse). So the years 1989 and 1990 did not have a reverse in the 3rd range.
I have a John Deere 1070, when in range 3 and I go to put it in reverse it will push the range shifter back to the center position. Does anyone know why this is happening?