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Casting Numbers for the Buick Turbo V6

Casting numbers are taken directly from parts believed to be correct. Several castings may be used during a production year or some castings may be used for various years. Use them as a guideline only! Unfortunately, most are well hidden when installed on the engine.  Intake manifolds are the best way to ID an unknown set up.

1978

CASTING NUMBERS (RWD):

• Intake - 1257407
• 4-barrel Plenum - 1258703 or 1261692
• Exhaust, Rt - 1256846

1979

CASTING NUMBERS (RWD):

• Intake - 1261568
• Plenum - 25501542
• EGR manifold - 1258700
• Turbo (Reman) - 25516900
• Turbine A/R - 0.82
• Compressor A/R - 0.42
• Exhaust, Rt - 1261620
• Exhaust, Lt - 1263031 (NA is same)

1980

CASTING NUMBERS (RWD):

• Block - 25506397
• Intake - 25504240
• Plenum - 25504509
• Exhaust, Rt - 25502804 (similar to 1261620, but with O2 sensor boss)
• Exhaust, Lt - 1263031 (NA is same)
• California Models may use 1981 castings

1981

CASTING NUMBERS (RWD):

• Block -
• Intake - 25507680
• Plenum - 25507719
• EGR Manifold- 1258700
• Exhaust, Rt, - 25507802
• Exhaust, Lt - 25507801 (NA is same)
• Export Models may use 1980 castings

1982

CASTING NUMBERS (RWD):

• Block - 25506818
• Intake - 25510179
• Plenum - 25510089
• Exhaust, Rt, - 25507802
• Exhaust, Lt - 25507801 (NA is same)

1983

CASTING NUMBERS (RWD):

• Block - 25514290
• Intake - 25510179
• Plenum - 25510089
• Exhaust Crossover - 25515323

Sources:
Actual casting numbers taken from parts.

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