[Daves55Sedan]

The gearbox itself will probably bolt up to any '52 thru at least '59 Ford Y-block or I-block bellhousing and rear extension housings can be swapped from '52-56 (not because of length) but because these have the same speedo driven gear orientation. The 57 thru 59 rotate the speedo cable backwards so they can't be used on '52-'56 cars (unless plugging in a Thunderbird speedo cable) which reverses the rotation back.
Also, the '52-'56 speedo drive gears have the worm teeth oriented properly only for '52-56 speedo cable/gear assemblies. The '57-'59 speedo drive gear is wound in opposite direction.
In order to use a '52-56 trans in a '57 or later car, one would need to get a '57 and later speedo drive gear and mating '57 and later speedo cable/gear assembly and also swap out the aluminum rear extension housing with a '57 and later housing. If this is not done, the '57 or later car speedometer will not register speed or mileage. It is disabled.
Not sure about front splines but I believe all the standard trans of the era fit the same clutch and there were several clutch sizes available (but you had to have the flywheel that fit that clutch housing as they used different bolt circles).
Pretty sure all the rear splines were same too, but the Fordomatic trans had different splines. Even if they did not match a driveshaft front yoke, you could always get a front yoke to match the trans tailshaft and put it on your driveshaft.
I believe Ford had different bellhousings for the V8 and 6-cyl, the V8 having a larger bolt circle to bolt to the back of engine block. Not 100% sure.