4.57 sounds right.
Tops out at 45 mph, which is speed limit of
short drive to work. I had a '65 Ch with an
4.10 Eaton partial-locker which exploded one day.
My brother found a 2.83 ( ? or somewhere around there )
and it made a huge difference.
Actually used granny low off the light.
4.57 only good for parades and farm work.
(bought it in Wy, hence the corn field in pic)


1960 C20 Platform