The engine identification code consists of the engine assembly plant, the engine assembly date, and a 2 or 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.

T = Tonawanda Engine Plant
0114 = January 14
TW = 402/350 L34 w/TH400 (Note on this Atlanta P-O-P the engine is coded with the two letter suffix TW.)

Engine Assembly Plant - 1st letter

Code Assembly Plant
 V Flint, Michigan
K McKinnon Industries
*T Tonawanda Engine Plant
Assembly Month - 1st and 2nd numbers
Number Month Number Month
*01 *January 02 February
03 March 04 April
05 May 06 June
07 July 08 August
09 September 10 October
11 November 12 December

Assembly Day - 3rd and 4th numbers




Code Size HP  
CCK 250-1 155 TH-350 Taxi, Police
CCL 250-1 155 Manual-3 Taxi, Police
CCM 250-1 155 Powerglide Taxi, Police
307 ↓        
CNC 307-2 200 Manual-3/4  
CND 307-2 200 Manual-4  
CNE 307-2 200 Powerglide  
CNF 307-2 200 TH-350  
CNG 307-2 200 Manual-3 Low Compression Engine
CNH 307-2 200 Powerglide Low Compression Engine
350 ↓        
CNI 350-2 250-L65 Manual-3/4  
CNJ 350-4 300-L48 Manual-3/4  
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 4-speed Monte Carlo
402 ↓        
CGR 402-4 330-LS3 Manual-3/4 Found on Vintage Vehicle Services Report
CKN 402-4 330-LS3 TH-400  
CKO 402-4 375-L78 Manual-4  
CKP 402-4 375-L78 (w/L89) TH-400 Aluminum Heads
CKQ 402-4 375-L78 Manual-3/4 Heavy Duty Clutch
CKR 402-4 330-LS3 Manual-3/4  
CKS 402-4 330-LS3 Manual-3/4 Heavy Duty Clutch/LS3
CKT 402-4 375-L78 (w/L89) Manual-3/4 Aluminum Heads
CKU 402-4 375-L78 (w/L89) Manual-3/4 Heavy Duty Clutch/Aluminum Heads
CTW 402-4 350-L34 TH-400  
CTX 402-4 350-L34 Manual-3/4  
CTY 402-4 375-L78 TH-400  
CTZ 402-4 350-L34 Manual-3/4 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 4-speed  
CRU 454-4 360-LS5 Manual 4-speed 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

(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. 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 and one registrant here has a dealer bill-of-sale plus the warranty Protect-O-Plate card both showing the CRY code.

(2) One source, Chevrolet by the numbers, shows CRN for a 1970 Monte Carlo 454/360 with TH400 where another source, Chevelle, Malibu & El Camino ID numbers 1964-87 shows the CRN code for a manual/4-speed.  Every Chevelle LS5 build sheet I have shows RT for an LS5 w/manual transmission and RQ for an LS5 w/TH400.  A Monte Carlo LS5 build sheet shows RN for an LS5 w/TH400.  I'll take the information on a build sheet over other published data.