Ben, thanks, we were told by a used dealer that they are possibly interchangeable except for the torque converter. Can you tell me about the 4 different versions of the F model transmissions, we work in a light duty application and only rarely use first gear [but it's needed occasionally]They will probably fit in place of each other but there are internal differences. The E series transmission is lighter duty the the F series and there are at least 4 versions of the F series transmission