1970 Chevelle Engine ID Codes - Engine Pad

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The engine identification code consists of the engine assembly plant, the engine assembly date, and 3 letter suffix indicating the cubic inch displacement, the horsepower rating, and generally, what type of transmission was to be installed with the engine. Manual transmissions required a bushing in the rear of the bellhousing where an automatic transmission did not. Many engine "accessories" such as the carburetor, distributor, and exhaust manifolds were not installed at the engine assembly plant but rather at the final assembly plant.

Notes:

⁽¹⁾ There is some discussion about the 454 being sold with 454 engines and aluminum heads. One very respected source says that according to records at Tonawanda no 454 with aluminum heads were assembled. Their records indicate the L89 option was cancelled (not replaced) with the demise of the L78/L89 combination. On the other hand, some have reported seeing the CRS code on engine blocks but whether these are legit or not is questionable.

⁽²⁾ One source, Chevrolet by the numbers, shows CRN for a 1970 Monte Carlo 454/360 with TH400 where a second source, Chevelle, Malibu & El Camino ID numbers 1964-87 (as well as many websites) shows the CRN code for a manual/4-speed Chevelle, and finally Chevelle and El Camino ID Model Codes (NCOA purple book) does not show this engine code at all probably due to the fact it's a Monte Carlo only engine.  Every Chevelle LS5 build sheet I have shows RT for an LS5 w/manual transmission (26 to date) and RQ for an LS5 w/TH400 (another 26).  Four Monte Carlo LS5 build sheets shows RN for an LS5 w/TH400.  I'll take the information on a build sheet over other published data.

These figures are for the U.S. production of Chevelles only (unless otherwise indicated) and does not include the Monte Carlo.
A total of 39,207 6-cyl engines were installed; 29,791 in U.S. built Chevelles and 10,416 imported from Canada.
A total of 413,255 8-cyl engines were installed; 198,285 307cid, 150,745 350cid, and 64,225 402/454cid engines.

* Monte Carlo exclusive

CGR engine suffix has been noted on a Canadian-built LS3 Chevelle with manual transmission.
CRF engine suffix has been noted on a Canadian-built L34 Chevelle with manual transmission.

How this 64,225 figure of combined 402/454 engines was arrived at is not known. Given the number of Z25 and Z15 options (including optional L78 and LS6 engines), the total arrived at is 63,372 for SS optioned Chevelles but this total includes the two SS options both exported to and imported from Canada so the exact U.S. figures are difficult to ascertain.

Vintage Vehicle Services documents indicate that of 10,176 Malibu Sport Coupes built in Canada for sale in Canada, 700 were equipped with the L34 engine.

Vintage Vehicle Services documents indicate that 3,306 Z25 optioned Malibu Sport Coupes with 1,750 ZL2 hoods along with 299 Z15 (LS5 only) optioned Chevelle Sport Coupes were exported for sale to the U.S.

Vintage Vehicle Services documents indicate that of the 25,938 V8 Malibu Sport Coupes built, 992 were ordered with the M20 and 2,152 with the U14 gauge package.

In addition to these imports and exports, a total of 9,338 LS3 engines must be accounted for somewhere in this 64,225 402/454 engine figure.
 
53,599 - Z25 SS396 options ordered (51,455 base L34 plus 2,144 optional RPO L78)
  8,773 - Z15 SS454 options ordered (4,298 base LS5 plus 4,475 optional RPO LS6)

Chevrolet only reports 442,046 engines and transmissions on the Accumulative Production Report of August 31, 1970. This number is only for U.S. built Chevelles. There is no breakdown of engines or transmissions imported from Canada.