Block Casting Number

Engine Model

Year Range

10212339

LS1 (5.7L/346ci)

1997-1998

12558805

LS1 (5.7L/346ci)

1997-1998

12559852

LS1 (5.7L/346ci)

1999-2001

12564241

LS1 (5.7L/346ci)

2001-2004

12564243

LS6 (5.7L/346ci)

2001-2005

12564243

LS2 (6.0L/364ci)

2005-2007

12600821

LS3 (6.2L/376ci)

2008-Present

12578452

LS7 (7.0L/427ci)

2006-Present

12621771

LS9 (6.2L/376ci)

2009-Present

12559862

LS1/LS6 (5.7L/346ci)

1999-2003*

12561706

4.8L/5.3L Cast Iron

2004*

12562317

4.8L/5.3L Cast Iron

2001-2006*

12572317

6.0L Cast Iron

2001-2006*

12572035

6.0L Cast Iron

2001-2006*

*Year Range Listed is for Known Years only.

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Site Updated: 8/28/17

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Southern Performance Systems
Phone: 678-482-0866
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Today's Muscle Engines for Yesterday's
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This page list some of the Casting Numbers for LS Series Engine Blocks and Heads. This is only a short list but we plan on continuing to expand on the list over time.

The Casting Number for a LS Series Block is located on the rear of the block just below the drive side head. (See Image) However, occasionally the cast number may be located on the Passenger Side. The last 3 or 4 digits of a head's casting number are located on the lower-right side of the head. (See Image)

Block Casting Number

Engine Model

Year Range

12550592

LS1 (5.7L/346ci)

1997

12559846

LS1 (5.7L/346ci)

1998

12559090

LS1 (5.7L/346ci)

1998

12562174

LS1 (5.7L/346ci)

1998

12559846

LS1 (5.7L/346ci)

1998

12560621

LS1 (5.7L/346ci)

1998

1240030

LS1 C5R (5.7L/346ci)

C5R Racing Block

12559378

LS1 (5.7L/346ci)

1999-2000

12561168

LS1/LS6 (5.7L/346ci)

2001

12561166

LS1/LS6 (5.7L/346ci)

2001-2004

12568952

LS2 (6.0L/364ci)

2005

12560799

LS2 (6.0L/364ci)

2006-2007

12584724

LS3 (6.2L/376ci)

2008-Present

12598723

LS7 (7.0L/427ci)

2006-Present

12621766

LS9 (6.2L/376ci)

2009-Present

12569513

5.3L Aluminum

2005*

12551358

4.8L/5.3L Cast Iron

1999-2003*

12551364

6.0L Cast Iron

1999-2004

*Year Range Listed is for Known Years only.

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