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TRANSMISSION IDENTIFICATION
The transmission identification code will differ depending the type of
transmission - Manual, Powerglide, Turbo Hydra-Matic 350 or Turbo Hydra-Matic
400.
The manual and Powerglide will have a production code consisting of a
prefix letter designating the assembly plant, a production date (year/month
letter/day number) and a shift code for day or night shift if the assembly
plant was using two shifts.
The Turbo Hydra-Matic 400 used a different date coding format. This production
code consists of a two-digit model year (70) followed by an engine/model
code letter and a three-digit production date. The three-digit production
date begins with the first day of January, 1969. For example, a production
date of 298 would be October 25, 1969 or, the 298th day of the 1969
calendar year. January 1 of 1970 would
be 366. A
Julian date calendar can be found here to assist you. Remember, a production
date of 001 to 365 is calendar year 1969
and 366 or higher is calendar year
1970. If the production date is over 365, subtract 365 and find the corresponding
Julian date for 1970. It's not known when the last TH400 was installed
in a 1970 Chevelle, but assuming July 31 the last model build day, a date
of 577 should be the largest date. July 31, 1970 (577) is the 212th day
of 1970. Subtracting 365 from 577 gives you 212 - July 31, 1970.
| Manual, Powerglide, Turbo Hydra-Matic 350 Transmission
Designations |
| 3-speed |
4-speed |
Powerglide |
Turbo Hydra-Matic 350 |
K - McKinnon Industries
S - Muncie |
P - Muncie (H.D. aluminum case)
R - Muncie (L.D. aluminum case) |
C - Cleveland
E - McKinnon Industries |
B - Cleveland
Y - Toledo |
| A typical Muncie
will break down as follows: P0A01A breaks down
to P (Muncie), 0 (1970 model year), A (January), 01 (day), A (M20)
. Any Muncie build in calendar
year 1969 for an August through December built 1970
model year would be dated with
M, P, R, S or T (Aug., Sep., Oct., Nov., Dec.) such as P0R25A meaning
the transmission was coded for a 1970 model year Chevelle on October
25, (calendar year) 1969. The letter suffix code identifies the
M20, M21, and M22; "A" for the M20, "B" for
the M21, or "C" for the M22. |
| Year - 0 |
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| Calendar Month |
| M - August |
P - September |
R - October |
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| S - November |
T - December |
A - January |
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| B - February |
C - March |
D - April |
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| E - May |
H - June |
K - July |
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Day Number
1...31 |
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Powerglide 2-speed and Turbo Hydra-Matic 3-speed
Automatic Transmission
B - Cleveland (TH350)
C - Cleveland (PG)
Y - Toledo (TH350)
Variations have been found for Powerglide and TH350 transmission
designations. Normal code would be the plant letter, model year,
month/day such as B0C14 for Cleveland (B), 1970 (0) March 14 (C14).
A Turbo Hydra-Matic 350 would be coded like Y0E01 for Toledo (Y),
1970 (0), May 1 (E01). |
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Turbo Hydra-Matic 400 Transmission Designations
*A sample TH400 code would be 70CF379 where CF indicates
a Chevelle 396 engine, CS (454/360) and CY (454/450) indicates a
H.D.TH400 and 379 indicates January 14, 1970. Since the
three digit suffix is greater than 365, the date must be in calendar
year 1970. Subtracting 365 from the 379 number gives a result of
14 indicating the 14th of January. Many times the P-O-P may just
code the single letter "F", "S", etc. instead
of "CF" or "CS".
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