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Exhaust Manifold Casting Numbers - Chevelle Specific

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Big block V8: 348, 366, 396, 409, 427, 454

V8 Exhaust Manifold Casting Month Codes
A - January	B - February	C - March	D - April
E - May	F - June	G - July	H - August
I - September	J - October	K - November	L - December

Caveats to production dates. Due to inventories, shipping schedules, etc. it is entirely possible that exhaust manifolds being phased out of production may still appear on Chevelles built after that time.

Manifold Number	Year	Engine	Horsepower	Outlet Size	Outlet Side	Notes
3834947	1964 1965 1966	283 327 283 327 283 327	195, 220 250 195, 220 250, 300, 350 195, 220 275	2.026	LH	First "log" type used on Chevelle. w/o A.I.R. w/o A.I.R.
3840715	1964	327	300, 365	2.46	LH	One year only design. "Log" type with generator bracket, bell bottom, high performance.
3840912	1965 1966	283 283 327	195 195 275	1.96	RH	Type 1. "Log" type with rear outlet. No heat tube, no A.I.R.
3840912	1965 1966	283 327 283	220 250, 300, 350 220 w/o A.I.R.	1.96	RH	Type 2. Identical to type 1 except it was drilled for heat tube.
3840912	1964	327	300	1.96	RH	Type 3. Outlet machined to a larger bell bottom shape, rear outlet and drilled for heat tube.
3868874	1965 1966 1967	396 396 396	375 325, 360, 375 325, 350, 375	2.526 2.526 2.526	RH	1965 and 1966/67 have same casting numbers but 1965 units do not have boss for A.I.R. but only 1966/67 Chevelles that used A.I.R. were drilled and tapped.
3869925	1965	396	375	2.526	LH	Bosses present for heat tube, no A.I.R.
3872729	1966	283 327	195, 220 275	2.026	LH	Identical to #3834947 except drilled & tapped for A.I.R.
3872730	1966 1967 1968	283 327 283 327 307 327	195, 220 275 195 275, 325 200 250, 275, 325	1.96	RH	Identical to #3840912 (type 2) except drilled & tapped for A.I.R. 1967 - w/A.I.R. 1968 - S/T w/A.I.R.
3872730	1966	283	220	1.96	RH	Same as above except drilled for heat tube.
3883999	1966	396	325, 360, 375	2.526	LH	One year only, used until June 1966. Has A.I.R. bosses but only those equipped with A.I.R. are drilled & tapped.
3892679	1967 1968	283 327 307 327	195 275, 325 200 250, 275	2.026	LH	Without A.I.R. 1968 - A/T w/o A.I.R
3892683	1967 1968	283 327 307 327	195 275, 325 200 250, 275, 325	2.026	LH	Same as #3892679 except drilled & tapped for A.I.R. 1968 - S/T w/A.I.R.
3893608	1967 1968	283 327 307 327	195 275, 325 200 250, 275	1.96	RH	Casting changed from #3840912 sometime late 1966 or early 1967 but date not known. Non-A.I.R.
3902401	1966 1967	396 396	325, 360, 375 325, 350, 375	2.526	LH	June 1966 through March, 1967 - cast from June 1966 through December 1966. Used for both A.I.R. and non-A.I.R.
3909879	1967 1968 1969 1970	396 396 396 427 402 454	325, 350, 375 325, 350, 375 325, 350, 375 425 (COPO) 330, 350, 375 360, 450	2.526	LH	Replaced #3902401 in March, 1967.
3909880	1967	396	325, 350, 375	2.526	RH	Used from approximately January through June of 1967.
3916178	1967 1968 1969 1970	396 396 396 427 402 454	325, 350, 375 325, 350, 375 325, 350, 375 425 (COPO) 330, 350, 375 360, 450	2.526	RH	Same as #3909880 with minor interior & exterior casting changes. Entered production in early June 1967.
3932376	1969 1970	350 307 350	250, 255, 300 200 250, 300	1.96	RH	"Log" type. Identical to #3946826 except not drilled & tapped for A.I.R. A/T w/o A.I.R.
3942527	1969	307 350	200 250, 255, 300	2.026	LH	Identical to #3942529 except drilled & tapped for A.I.R. S/T w/A.I.R.
3942529	1969 1970	307 350 307 350	200 250, 255, 300 200 250, 300	2.026	LH	Identical to #3942527 except not drilled & tapped for A.I.R. A.T w/o A.I.R.
3946826	1969	307 350	200 250, 255, 300	1.96	RH	Identical to #3932376 except drilled & tapped for A.I.R. A/T w/A.I.R.
3959562	1972	307 350	130 NB2 165, 175 NB2	2.026	RH	Identical to #3973432 except drilled & tapped for A.I.R. NB2 equipment required on California vehicles, A.I.R. system and camshaft with longer valve overlap.
3973432	1971 1972	307 350 307 350	200 245, 270 130 w/o NB2 165, 175 w/o NB2	2.026	RH	Casting #3959562
3989041	1972	307 350	115 145, 175	2.026	LH	Identical to #3989403 except drilled & tapped for A.I.R. A/T w/A.I.R.
3989043	1971 1972	307 350 307 350	200 245, 270 130 165, 175	2.026	LH	Identical to #3989401 except not drilled & tapped for A.I.R. A/T w/A.I.R. Casting #3989401 after 10/19/71.
3989310	1971 1972	402 454 402 454	300 365 240 270	2.526	RH
3989343	1971 1972	402 454 402 454	300 365 240 270	2.526	LH