1970 SS396/SS454 Breakdown by Engine
RPO Z25 Breakdown
We are often asked by owners questions like, "How many LS6 convertibles were built?" Breaking any of the SS engines down by body style can only be done by a mathematically even calculation based on the number of each engine sold by each body style that could get the option. For example, first we must take the advertised number of Malibu sport coupes sold (289,622), Malibu convertibles sold (7,141) and Malibu El Caminos sold (40.728) and calculate the percentage of the SS454 option could have been ordered in a given body style. In the table below, are rounded off where the total SS396 options are 53,599 and the total SS454 options are 8.773.
| Malibu Body Styles | Total Sold | Percentage | SS396 | SS454 |
| 53,599 | 8,773 | |||
| Malibu Sport Coupe | 289,622 | 85.82% | 49,997 | 7,529 |
| Malibu El Camino | 40,728 | 12.07% | 6,468 | 1,019 |
| Malibu Convertible | 7,141 | 2.17% | 1,134 | 186 |
| Total Malibus Possible | 337,491 | |||
One then can break down the number of SS396 L34 vs L78 engines in each calculated body style where L34 sales are 51,455 and L78 sales are 2,174.
| Malibu Body Style | Total Sold | Percentage | L34 (base) | L78 |
| 51,455 | 2,174 | |||
| Malibu Sport Coupe | 289,622 | 85.82% | 44,157 | 1,840 |
| Malibu El Camino | 40,728 | 12.07% | 6,210 | 259 |
| Malibu Convertible | 7,141 | 2.17% | 1,089 | 45 |
| Total Malibus Possible | 337,491 | |||
RPO Z15 Breakdown
The same cam be done with the SS454 LS5 vs LS6 engines in each calculated body style where LS5 sales are 4,298 and LS6 sales are 4,475.
| Malibu Body Style | Total Sold | Percentage | LS5 (base) | LS6 |
| 4,298 | 4,475 | |||
| Malibu Sport Coupe | 289,622 | 85.82% | 3,688 | 3,840 |
| Malibu El Camino | 40,728 | 12.07% | 519 | 540 |
| Malibu Convertible | 7,141 | 2.17% | 91 | 95 |
| Total Malibus Possible | 337,491 | |||
About The Numbers
Given the calculations above, does this mean they are true and accurate? As far as calculations go, yes they are accurate. Are they the true numbers of productions? No - unless by some quirk of fate they match actual production numbers which is highly unlikely.
What About Other Options?
When you get into combinations such as how many LS6 convertibles were optioned with a 4-speed and the ZL2 hood? Sure, one can use the number of M22 transmissions (5,410) and ZL2 hood options (26,888) but think again. The M22 was also a mandatory transmission for the LS5 and well as the LS6. Breaking those two down by engine is possible but and maybe even engine and body style. The ZL2 hood option, well, not so much since the ZL2 could be ordered with the SS396 option as well.
The same would hold true for the M20/M21 4-speed or TH400 Turbo Hydra-Matic. The M20 and M21 (26,131 and 11,830 respectively) could be ordered with more engines than the L34 and L78. The TH400 (43,748) could be ordered with more engines than the L34, L78, LS5, and LS6. Specific exterior colors and/or interior seat type/color are impossible to calculate.
So the next time somebody tells you their black LS6 convertible with a red bucket seat interior with a TH400 and ZL2 hood option is 1 of 5 (or any other number), take it with a grain of salt. Extensive research may show it's 1 of 5 they may know of, that's where it ends.
There were five different TH400 transmissions used in 1970 based on
the horsepower rating of the engine so one could tell if the TH400 in
their Chevelle was original to the car and with a matching, correct
partial VIN stamp, determine if their Chevelle was a true SS396 or SS454.
The identifying letters on the TH400 transmission were on a metal plate
affixed to the transmission case itself. The example here is a high-shift
point TH400 as noted by the "CY" letters. Additional information stamped
on the tag are the transmission assembly date, 413, and the serial number
of the transmission, 1928. The 413 date is a Julian date beginning with
the calendar year 1969; the 413th day from January 1, 1969 is February
17, 1970.
TH400 Transmission Codes
CF - L34 engine
CR - LS5 engine found on Van Nuys LS5s prior to at least 01-04
CS - LS5 engine
CW - L78 engine
CY - LS6 engine (high shift point)
The same procedure shown here for 1970 can be applied to any year when trying to break down colors, engine/transmission options possibilities. The best you can do is calculate an even distribution of a single item; combining two or more dilutes the resulting answer and one might just as well guess.
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1970 Chevelle SS396/SS454 Build Sheet Decode Program 1964-1972 Ship Manuals & Parts Catalog 1953-1972 Chevrolet Production Numbers |
