1970 Chevelle Engine ID Suffix Codes

 

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, alternators, and power steering units were not installed at the engine assembly plant but rather at the final assembly plant.

 

Engine stamp samples

 

1964

1965

1966

1967

1968

1969

1970

1971

1972

Engine			Transmission	Notes
Code	Size-Carb	HP-RPO
CRF	250-1	155-L22	Manual
CCG	250-1	155-L22	Powerglide
CCK	250-1	155-L22	TH-350	Taxi, Police
CCL	250-1	155-L22	Manual	Taxi, Police
CCM	250-1	155-L22	Powerglide	Taxi, Police
307 ↓
CNC	307-2	200-L14	Manual
CND	307-2	200-L14	Manual
CNE	307-2	200-L14	Powerglide
CNF	307-2	200-L14	TH-350
CNG	307-2	200-L14	Manual	Low Compression Engine
CNH	307-2	200-L14	Powerglide	Low Compression Engine
350 ↓
CNI	350-2	250-L65	Manual
CNJ	350-4	300-L48	Manual
CNK	350-4	300-L48	Powerglide
CNM	350-2	250-L65	Powerglide
CNN	350-2	250-L65	TH-350
CRE	350-4	300-L48	TH-350
400 ↓
CRH *	400-2	265-LF6	TH-350	Monte Carlo
CZX *	400-2	265-LF6	Manual	Monte Carlo
402 ↓
CGR	402-4	330-LS3	Manual	Found on Vintage Vehicle Services Report
CKN	402-4	330-LS3	TH-400
CKO	402-4	375-L78	Manual
CKP	402-4	375-L78 (w/L89)	TH-400	Aluminum Heads
CKQ	402-4	375-L78	Manual	Heavy Duty Clutch
CKR	402-4	330-LS3	Manual
CKS	402-4	330-LS3	Manual	Heavy Duty Clutch/LS3
CKT	402-4	375-L78 (w/L89)	Manual	Aluminum Heads
CKU	402-4	375-L78 (w/L89)	Manual	Heavy Duty Clutch/Aluminum Heads
CTW	402-4	350-L34	TH-400
CTX	402-4	350-L34	Manual
CTY	402-4	375-L78	TH-400
CTZ	402-4	350-L34	Manual	Heavy Duty Clutch
454 ↓
CRN * (2)	454-4	360-LS5	TH-400	Monte Carlo
CRQ	454-4	360-LS5	TH-400
CRR	454-4	450-LS6	TH-400
CRS (1)	454-4	450-LS6(w/L89)	TH-400	Aluminum Heads
CRT	454-4	360-LS5	Manual-M22
CRU	454-4	360-LS5	Manual-M22	Heavy Duty Clutch
CRV	454-4	450-LS6	Manual-M22
CRX	454-4	450-LS6	Manual-M22	Heavy Duty Clutch
CRY (1)	454-4	450-LS6(w/L89)	Manual-M22	Aluminum Heads/Heavy Duty Clutch

Notes:

⁽¹⁾ There is always some discussion about the 454 being sold with 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-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, 150,745 350-cid, and 64,225 402/454-cid 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 SS 396 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.

 

If the radiator support hasn't been changed or the emission/tune up labels haven't been replaced with aftermarket items, here are a few examples of those emission/tune-up labels. For the 402 and 454 engines these will vary by the time of year. For example, the DQ label for the L34 and KS5 with automatic transmission as typically used through early March when it was replaced with labels AT for the L34 with automatic transmission and AW for the LS5 with automatic transmission. See my webpage at  70emission_label.htm  for more on engine label engines and dates used.

 

 

The 375hp L78 engine was dropped around November of 1969 with the introduction of RPO Z15 which offered a 360hp 454cid engine. With the cancelation of the L78 engine, the L89 aluminum head option was also canceled. Only 18 L78s were also optioned with the L89 aluminum heads.

 

The RPO LS6 450hp engine was an option when RPO Z15 was ordered. The LS6 engine option was an additional $263.20 on top of the Z15's $503.45 cost. Both the LS5 and LS6 also mandated one of two transmissions, the RPO M40 TH400 3-speed automatic transmission ($290.40) or the heavy duty close ratio M22 4-speed transmission ($264.00).

 

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