ID/ Casting
Code Year(s) CID Number Notes
A '65 425 381917?? 1st year, big cars.
386525
B '65 400 389298 442 only, one year only.
D '66 - '67 425 389244 Big-car engine. Toro is different internally.
E '66 - '67 400 390925 442 engine [VERY rare].
F '68 - '72 455 396021 Most common big block. Two types of "F"
letters: stick type, and one with two vertical
hangers and a base.
Fa '72 - '76 455 396021 Very common big block.
G '68 - '69 400 396026 442/Vista/etc. engine.
L '76 455 231788 Motorhome, maybe marine also. GM made motorhomes
from '73-8, maybe in all?
Please refer to the Engines
section as well!
Look for the casting number and letter on the horizontal shelf right
behind the water pump, just to the [driver's] right of the oil pressure
sensor. The casting numbers are usually about ¾" - 1" tall, and the ID/Code is usually a bit larger, a little over an inch, and covered with
schmutz. The most
common block will be the standard 455: "396021 F" or "396021
Fa". The "a", as in Fa, is actually an upper case A, but
about ¼ as big as the F, and subscript to the F [set lower]. Also, on
the 231788L block, the "L" is the same size as most of the rest
of the digits, whereas the center "7" is noticeably smaller.
400's were bronze in color, most 425's and early 455's (1968, 1969) were
red, while Toronado 425's and later 455's were blue. However, since engine
color may have been changed, use this as supporting evidence only.
[ Thanks to Chris Witt, Ed Ekstrom, Daren for this information ]