Early vs late model 7.3 block strength and crankshaft design

There are, however, two different DI blocks.
The first series design is readily identified by
the lack of solid webbing in the valley up to the
deck of the block (Figure 6). So if you’re looking
down on the deck toward the lifter bores it is
one big opening.
The second series block (c/n 1825849C2) is
used from mid-1998-2004 with serial number
661,974 through 2,030,402. This block received
some structural improvements such as additional
crank counterweight clearance in the lower
crankcase. The visual identifiers are the full
casting separations between each cylinder in the
lifter valley to the block deck (Figure 7).

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The direct injection engines get a little more
interesting. Riddle me this: when are three different
crankshafts actually two? When they are
used in the 7.3L DIT engine.
The first two crankshafts are considered the
same product. The only difference between them
is the size of the hole bored into the rod throws.
One (c/n 1818200C1) has 1-1/8˝ bore balance
holes in the rod throws and the other (c/n
1818200C3) has 1˝ bore balance holes drilled in
them. The diameter of the balance hole was
changed for better strength and reliability.
Despite this difference, these cranks are considered
the same and are fully interchangeable
(Figure 9). Use either of these cranks in serial
number engines 501 through 661,973.

The third crank (which is actually
the second design) has no
balance hole in the rod throw at
all and has a slightly different
configured counterweight. This
crank can only be used in the
later block casting (c/n
1825849C1) which has the
clearance (Figure 10). This
crank is used in serial number
661,974 through 2,030,402

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