I do not know about 1957 (so, you might want to ignore the rest of this post).

You can remove the Hydra-Matic transmission and straight 6 engine out the front of an 54/55st A-D truck , as “one piece”:
- make sure your lift can handle the total weight
- remove the hood
- remove the grill
- remove the radiator
- remove the radiator housing
- support the engine transmission “as appropriate”, and remove the rear-engine and transmission cross members
- disconnect the driveshaft
- slowly/carefully remove the transmission-engine assembly
- say a prayer, if you believe in the power of prayer

Take photographs.