Well, you may have saved me from a big mistake. I have a 57 Fordomatic Transmission Manual and don't see anything labeled as a one-way clutch in the diagrams. It does mention a "forced downshift" to 1st when floored under 16MPH. Here is the rest of the instruction I found:
"You need a valve body from a COM of the mid '60s to mid '70s. The post '67s will be FMXs. Look for a vacuum modulator on the back of the case on the shift lever side. Pre-FMXs will have a shift indicator on the dash with two drive ranges and a low. In one drive range it takes of in 1st, in the other it takes off in 2nd. FMXs have a D-2-1 shift pattern, always take off in 1st. You also need the detent from the shift lever inside the case. Some call it a "rooster comb", it does look like one. The valve body and detent are installed in your trans, they're bolt-ins. The detent is irksome, the spring loaded ball keeps wanting to pop out of its bore and roll under the bench or into a floor drain. Some FMXs have a rounded pin instead of the ball, it's a lot easier to install. The valve body may block the passages to the rear pump, but no matter. I ususally take the outer gear of the pump out to reduce drag, leave the inner one in as a spacer. You can no longer push start the car. You have to drill and tap the case to accomodate the vacuum modulator, which is connected to intake manifold vacuum. Use the COM case to measure the location of the hole. Your '57 water cooled should have the internal one way clutch, so should be OK. Your shifter may not have enough travel to reach manual 1st, can probably be reworked to do this, but for normal driving you don't need manual low anyway. I have this in my '56 Bird and it works well. Really helps it step away from stoplights in city traffic. Less load on the engine, less load on the transmission, so less heat generated. Too bad Warner Gear didn't do this with the very first FOMs, would have eliminated a lot of bad press in the early '50s Fords. The modulator also eliminates the "bang" you get when you shift from N to Dr or R."