My 4-speed 69 Barracuda coupe has both front and rear torque boxes.
It is total hit-and-miss on 4-speed cars. My 69 383 4-speed GTS has them front and rear but that seems to be the rare case as I have seen many more 4-speed A-Body's with just rears.
The funny thing about science is that if you change one miniscule parameter you change the entire outcome to the way you want it.