The Casting Numbers to the right are found just below and to the right of the Distributor on the passenger side. They are notoriously
very hard to read and often people make the mistake of thinking a '3' is an '8'. Clean the area thoroughly and use a nice bright
flashlight. This is usually a 7 digit number and each letter/number is about 1/2" tall. A little engine degreaser and a wire brush often
makes this job easier.
The next numbers we need are the ones just below the Starter on the passenger side. This one will have a CONveyor Number and beside that
a usually four digit letter/number combination separated like this: X XX X. For example, the first X will be a Letter from A through L.
A = January through L = December. The center two digits are the day of the month. The final digit is the year the engine was made WITHIN
the years that you narrowed it down to when you deciphered the Casting Numbers to the right.
The next set of numbers you will find helpful are on the flat part of the Distributor Deck. This machined flat area has serial numbers
stamped into it. If you have looked very carefully and find no numbers there, chances are your block is classified as a Replacement Block
and will have no numbers stamped on that deck. The numbers you are looking for are stamped (about 1/4" high) and usually a Letter followed
by three Numbers and ending in another Letter (or two). The first letter is almost always F since most GM engines were made in Flint, Michigan. The
following numbers are the month first followed by the day of the month. The trailing letters denote what the engine was installed in. The
possible Letters for the last ones are explained in the chart below.
On the flat part of the Distributor Deck you will find a stamped Serial Number. The first letter will be either
F for Flint Michigan, or
T
for Tonowanda, New York. These were the two locations engines were manufactured at the time. The numbers behind the F (or T) designate the
Calendar month and date the engine was produced. The remaining letters are in accordance to the Type and Series of the vehicle the engine
came out of. This helps to tie the vehicle together with the engine. RPO's are Regular Production Orders. These standard Orders could include
many variables and Chevrolet had several of them that were popular with the Dealers. Here is the Car and Truck listings for 1954-1962:
PASSENGER CAR ID
- A - Regular Production with Standard 3 speed or Overdrive
- AE - Regular with heavy duty clutch (1119-1519 taxi cab)
- B - Regular with Powerglide (Hydraulic Lifters)
- Z - Regular Engine
- ZC - Regular Engine with HD Clutch
- ZH - Fleet - Aluminum Cam Gear
- ZJ - Fleet - Aluminum Cam Gear and HD Clutch
- Y - Automatic Transmission
TRUCK ID (all Solid Lifter Engines)
- J - 3100-3200-3800/CK 10-20, C30 Regular Production
- JA - CK 10-20, C30 with RPO 311
- JB - C10-20 with RPO 311
- JC - 4000 (31-32-36-3800 RPO 227)/C40 CK 10-20, C30 RPO 223
- JD - CK10-20, C30-40 with RPO 225 (HD Clutch)
- JE - C1402 with RPO 232
- JF - 31-32-36-38-41-4400 with RPO’s 314 & 321
- JG - P10 Base Engine
- JH - P10 with RPO 311
- JK - P10 with RPO 223
- K - 34-35-3700/P20-30
- KA - 34-35-3700 with RPO 321/P20-30 with RPO 321
- L - 6000/CLS50
- LA - CS50 with RPO 225
- LB - CLS60
- LC - 6000 with RPO 309/CS60 with RPO 225
- LD - 6000 with RPO 413/CL60 with RPO 413 & 585
- LE - 6000 with RPO 413 & 309/CLS60 with RPO 350
- LF - T60 Base Engine
- LG - T60 with RPO 350
- LJ - CLS60 with RPO 309
- LK - CLS60 with RPO 350 and Powermatic
- LM - C60 with RPO 413 & 585 and Powermatic
- LU - CLS60 with RPO 223
- LV - CS60 with RPO 225 and HD Clutch
- LW - CLS60 with RPO 223 and Power Steering
- LX - CL60 with RPO 223 and Air Brakes
- LY - T60 with RPO 223
- LZ - T60 with RPO 223 and Power Steering
- M - 31-32-36-3800-4000/CK10-20, C30-40 with RPO 408
- MA - 31-32-36-38-41-4400 with RPO 314,321 & 408
- MB - 31-32-36-38-4000 with RPO 227 & 408/CK10-20, C30-40(RPO 409)
- N - 5000 Regular Production/L50 with RPO 408
- NA - 5000 with RPO 309/L60 with RPO 408
- NC - 5000 with RPO 413
- ND - 5000 with RPO 309 & 413/T60 with RPO 408
- P - 6000 with RPO 408/C50-S50 with RPO 408
- PA - 6000 with RPO’s 309 & 408/C60-S60 with RPO 408
- PB - C50-S50 with RPO 409
- PC - 6000 with RPO 408 & 413/C60-S60 with RPO 409
- PD - 6000 with RPO 309, 408 & 413
- PJ - C60 with RPO 223 & 418
- PK - C60 with RPO 223, 408, 413-585
- PL - C60 with RPO 223, 408, 413-585
- PM - L60 with RPO 223 & 408
- PN - L60 with RPO 223 & 418
- PQ - L60 with RPO 223, 408 & 413-585
- PR - L60 with RPO 223, 408 & 413-585
- PS - T60 with RPO 223 & 408
- R - 7000 Regular Production (5000 with RPO 418)
- RA - 7000 with RPO 309 (5000 with RPO’s 309 & 418)
- RC - 5-7000 with RPO’s 413 & 585
- RD - 5-7000 with RPO’s 309, 413 & 585
- S - 8000 Regular Production (6000 with RPO 418)
- SA - 8000 with RPO 309 (6000 with RPO’s 309 & 418)
- SC - 6-8000 with RPO’s 309, 413, 585
- SD - 6-8000 with RPO’s 413 & 585
- T - 9000 Regular Production (7000 with RPO 385)
- TA - 9000 with RPO 309
- TB - M70-C70-S70-C80 with RPO 409
- TC - T70-T80
- TD - C-L-70-80-M-S-70 with RPO 309
- TE - T70-80 with RPO 309
- TF - CL70-80, MS70, S67 with RPO 385
- U - 10000 Regular Production (excludes 10800)
- UA - 10000 (excludes 8800-10800) with RPO 309
- V - R10 Base Engine
- VA - R10 with RPO 225
- W - R10 with RPO 667
- WA - R10 with RPO 225 and Automatic Transmission
