Know your MGB
CHASSIS (CAR) NUMBER, VIN & MAJOR UNIT SERIAL NUMBERS
The following illustrations show where the various identification/serial numbers are located on the MGB and MGB GT:
The MGB’s Timeline
MGB Roadster 1962-1980
3 Synchro (‘Mk 1′) 1963 to 1967 Model Years
GHN3-101 to 48766 (Jun. ‘62 to Oct. ‘64): 3 main bearing engine with dynamo, positive earth, 3 synchromesh gearbox.
GHN3-48767 to 138400 (Oct. ‘64 to Oct. ‘67): 5 main bearing engine with dynamo, positive earth, 3 synchromesh manual gearbox.
4 Synchro (‘Mk2 & Mk3‘) 1968 to 1980 Model Years
GHN4-138401 to 187209 (Nov. ‘67 to Oct. ‘69): 5 main bearing engine with alternator, negative earth, 4 synchromesh manual gearbox or automatic gearbox, last cars with chrome grille, last cars with BMC type interior trim with leather seats.
GHN5-187210 to 219000 (Oct. ‘69 to Aug. ‘70): Black recessed grille, first cars with ‘Leylandised’ vinyl interior trim, last cars with packaway hood or deluxe folding (grey frame) hood.
GHN5-219001 to 258000 (Aug. ‘70 to Aug. ‘71): Black recessed grille, last cars with 18G series engines, first cars with folding (black frame) hood.
GHN5-258001 to 294250 (Aug. ‘71 to Aug. ‘72): Black recessed grille, first cars with 18V series engines, first cars with centre console with armrest.
GHN5-294251 to 360300 (Aug. ‘72 to Sep. ‘74): Chrome/black honeycombe grille, first cars with cooling slots in front valance, last cars with chrome bumpers, last cars with overdrive switch on fascia.
GHN5-360301 to 410000 (Sep. ‘74 to Jun. ‘76): First cars with rubber bumpers, overdrive switch on column stalk, last cars with mechanical radiator fan.
GHN5-410001 to 501000 (Jun. ‘76 to Jun. ‘79): Overdrive switch on gear lever, first cars with electric radiator fan, commonly called ‘September 1976 on’ models (although the first car was built in June, the model was launched in September).
GV_DJ_AG-501001 to 523001 (Jun. ‘79 to Oct. ‘80): Cars with new international VIN (vehicle identification number) type serial number
MGBGT 1965-1980
3 Synchro (‘Mk 1’) 1965 to 1967 Model Years
GHD3-71933 to 139470 (Sep. ‘65 to Oct. ‘67): 5 main bearing engine with dynamo, positive earth, 3 synchromesh manual gearbox
4 Synchro (‘Mk 2 & Mk 3’) 1968 to 1980 Model Years
Mk 2 – GHD4-139471 to 187840 (Nov. ‘67 to Sep. ‘69): 5 main bearing engine with alternator, negative earth, 4 synchromesh manual gearbox or automatic gearbox, last cars with chrome grille, last cars with BMC type interior trim with leather seats.
Mk 3 – GHD5-187841 to 219000 (Sep. ‘69 to Aug. ‘70): Black recessed grille, first cars with ‘Leylandised’ vinyl interior trim, horn push on column stalk.
GHD5-219002 to 258003 (Aug. ‘70 to Aug. ‘71): Black recessed grille, last cars with 18G series engines, horn push back on steering wheel.
GHD5-258004 to 296000 (Aug. ‘71 to Aug. ‘72): Black recessed grille, first cars with 18V series engines, first cars with centre console with armrest.
GHD5-296001 to 361000 (Aug. ‘72 to Sep. ‘74): Chrome/black honeycombe grille, first cars with cooling slots in front valance, last cars with chrome bumpers, last cars with overdrive switch on fascia.
GHD5-361001 to 410350 (Sep. ‘74 to Jun. ‘76): First cars with rubber bumpers, overdrive switch on column stalk, last cars with mechanical radiator fan.
GHD5-410351 to 501035 (Jun. ‘76 to Jun. ‘79): Overdrive switch on gear lever, first cars with electric radiator fan, commonly called ‘September 1976 on’ models (although the first car was built in June, the model was launched in September).
GV_EJ_AG-501036 to 523002 (Jun. ‘79 to Oct. ‘80): Cars with new international VIN (vehicle identification number) type serial number.
MGB GT V8 1972-1976
GD2D1-101 to 2100 (Dec. ‘72 to Sep. ‘74): Chrome bumper models.
GD2D1-2101 to 2903 (Sep. ‘74 to Jul. ‘76): Rubber bumper models
Identifying your MG
To ensure the parts that you order are correct for your MGB or MGB GT, you will need to know most importantly the chassis number (models up to 1979) or VIN (vehicle Identification Number, 1980 models only). Additionally when ordering engine parts you will also need to know the engine number. Gearbox, overdrive and axle numbers may be required to order parts for those major units.
Chassis Numbers 1962-1979
Chassis number prefixes are as follows:
GHN3 MGB Roadster, 3 synchromesh, 1962-67
GHN4 MGB Roadster, 4 synchromesh, 1967-69
GHN5 MGB Roadster, 4 synchromesh, 1969-79
GHD3 MGB GT (4 cyl), 3 synchromesh, 1965-67
GHD4 MGB GT (4 cyl), 4 synchromesh, 1967-69
GHD5 MGB GT (4 cyl), 4 synchromesh, 1969-79
GD2D1 MGB GT V8, 1972-76
| First character – Make | G = MG |
| Second character – Engine Type | H = Engine Size between 1400cc & 2000cc |
| Third Character – Body Type | N = 2 seated Roadster or D = 2+2 GT (Coupe) |
| Fourth Character – Series | 3 = Mk1 (1962-1967) 4 = Mk2 (1968-1969) 5 = Mk3 (1970- June 1979) |
| Fifth Character – Market | U = USA & all left-hand drive Cars – 1970 (Mk3) onwards L = Left-hand drive (used upto end of Mk2 Cars – Sept. 1969) R = Right-hand drive (not used on UK Spec. cars) |
| Sixth Character – Model Year (North American Market Only) | None =1968-69 A =1969-70 B =1971 C =1972 D =1973 E =1974 F =1975 G =1976 H =1977 J =1978 L =1979 |
| Characters Seven to Twelve | Individual Car Number |
| Thirteenth Character (Mk2 Onwards) | G = Built at MG Factory Abingdon |
Example: A car showing GHN5UF376343G is – MG/MGB/USA spec. (Roadster body/1800cc B Series engine/LHD steering, manual gearbox/1975 model year/built Abingdon plant (MG factory)/serial no. 376343
Vehicle Identification Number (VIN) – June 1979 – October 1980
VIN (Vehicle Identification Number)
The last six characters of the VIN are the serial number of your car. However, the VIN also provides you with considerably more useful information, most importantly the model year of your car (most changes in production relate to model years). The complete VIN can be broken down thus:
| First character | G = MG marque |
| Second character | V = MGB model range |
| Third Character | A = UK spec. (Roadster) |
| G = UK spec. (GT) | |
| J = Japan spec | |
| L = Canada spec. | |
| V = USA Federal spec. | |
| Z = USA California spec. | |
| Fourth Character | D = Roadster body |
| E = GT body | |
| Fifth Character | J = 1800cc B Series engine |
| Sixth Character | 1 = RHD steering, manual gearbox |
| 2 = LHD steering, manual gearbox | |
| Seventh Character | A = 1980 model year |
| Eighth Character | G = Abingdon plant (MG factory) |
| Ninth to Fourteenth | 12345 = serial number Characters |
Example: A car showing GVGEJ1AG 501036 is – MG/MGB/UK spec. (GT)/GT body/1800cc B Series engine/RHD steering, manual gearbox/1980 model year/Abingdon plant (MG factory)/serial no. 501036
Identifying your Engine Number
The engine number will tell you far more than just the serial number of your engine
Engine No., 18G Series, 4 Cylinder Engine 1962-71
| First prefix | 18 = 1800cc |
| Second prefix | G = 3 bearing crank, open crankcase breathing |
| GA = 3 bearing crank, closed circuit breathing | |
| GB = 5 bearing crank, closed circuit breathing, dynamo | |
| GD = 5 bearing crank, closed circuit breathing, alternator | |
| GG = 5 bearing crank, carb feed breathing circuit, alternator | |
| GF = USA/Canada only | |
| GH – GK = USA/Canada only | |
| Third prefix (optional) | R = Overdrive |
| Fourth prefix | U = 3 synchro |
| We = 4 synchro | |
| Rc = automatic | |
| Fifth prefix | H = High compression |
| L = Low compression | |
| Remaining Digits | Serial number |
Example: An engine showing 18GD R We H 6001 is – 1800cc/5 bearing crank, closed circuit breathing, alternator/overdrive/4 synchro/high compression/serial no. 6001
Engine No., 18V Series, 4 Cylinder Engine 1971-80
| First prefix | 18V = 1800cc, in-line |
| Second prefix | 581F = Twin HS4 carbs, non-overdrive, 1971-73 |
| 581Y = Twin HIF4 carbs, non-overdrive, export, 1971-73 | |
| 582F = Twin HS4 carbs, overdrive, 1971-73 | |
| 582Y = Twin HIF4 carbs, overdrive, export, 1971-73 | |
| 583F = Twin HS4 carbs, auto | |
| 583Y = Twin HIF4 carbs, auto, export, 1971- | |
| 779F = Twin HIF4 carbs, non-overdrive, 1974 | |
| 780F = Twin HIF4 carbs, overdrive, 1974 | |
| 846F = Twin HIF4 carbs, non- overdrive, rubber bumper | |
| 847F = Twin HIF4 carbs, overdrive, rubber bumper | |
| 584Z to 673Z = USA/Canada only | |
| 836Z to 837Z = USA/Canada only | |
| 797AE to 893AE = USA/Canada/Japan only | |
| Third prefix | H = High compression |
| L = Low compression | |
| Remaining Digits | Serial number |
Example: An engine showing 18V 847F H 40101 is – 1800cc, in-line/twin HIF4 carbs, overdrive, rubber bumper/high compression/serial no. 40101
Engine No., 486 Series, V8 Engine 1972-76
| First prefix | 486 = 3500cc, 8.25:1 compression ratio, MGB installation (rear mounted HIF6 carbs, remote oil filter head) |
| Fourth to Eighth Digits | Serial number |
Example: An engine showing 48601301 is -3500cc, 8.25:1 compression ratio, MGB installation/serial no. 01301