Still At It,
Here is what I could find in searching the
GM Heritage Site Info Kits:
F0719J decodes as:
F = Flint plant 1957 Truck 235
07 = July
19 = 19th day of July
J = Installed originally in a 3400-3500-3700 Series truck (regular production)
KAA402952 decodes as:
K = 1952 216
A = Passenger car
A = Flint plant
402952 = assigned sequential serial number (factory numbers started with "1001")
In both cases, it would help if you could provide the block casting numbers for each engine as well as the casting date codes as those will help confirm what you have.
Dan
