F 55 7
F = Engine assembly plant Flint, Michigan
55 = Model Year 1955
7 is incorrect should be a letter, this will tell you type > truck or car
0004977 = unit number

Engine serial numbers

Casting Number 3837004, Not 38837004 one to many 8's
Manufacturer Chevrolet
Category Engine Blocks
Type Inline-6
Date 1955-1957
Notes 235 CID, Chevrolet

castingnumbers.info

1954 Chevrolet 3105 Deluxe Panel Truck
w/Factory HYDRA-MATIC