Do you know if the rod (for lenght) will also be different ???
45 shifter rods only fit 45s so it is hard to have a wrong one, other than early or late. One has a clevis, the other a hook. Big twin rods don't fit. But Big Twin shift gates definitely fit the holes in the tanks! Does your three speed gate have a big blank spot forward of the #1? If so it is Big Twin.