Mercruiser Block ID Codes – 6 Cylinder Engines
The model of Mercruiser Engine can be determined by looking at the last letters of the engine code which is stamped in all complete Marine Longblocks by General Motors at the time of assembly. If the serial number and/or model decals are missing, the Marine Engine code will help to determine the specific engine model/vintage. Refer to the drawing below for the engine code location of your Engine.
Information you need from the engine code, example M01187MH. 7=General Motor’s model year in this case 1997, BUT this could also be 1987 or 1977. MH = Type of engine. The 350 cid V8 Mercruiser models 5.7L, 350 Mag Mpi, Black Scorpion Ski, etc.
**GM 6 Cylinder 250 cid (4.1L) – Sterndrive Model (LH rotation), flat lifters
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 165 | SD | 1974–1980 | 12–3/4 (324) |
**GM V6 229 cid (3.8L) – Sterndrive Model (LH rotation), flat lifters
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 185 | JK | 1983–1984 | 12–3/4 (324) |
GM V6 262 cid (4.3L) with Mechanical Fuel Pump – Sterndrive Models (LH rotation)
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 185 | KD | 1985, 4K | 12–3/4 (324) |
| 185 | KW | 1985–1986, 5KW, start 14 in. flywheel, 6KW,start full circle rear seal | 14 (356) |
| 175 | KP | 1987, start roller lifter | 14 (356) |
| 205 | KJ | 1985, 4KJ | 12–3/4 (324) |
| 205 | KR | 1985–1987, 5KR, start 14 in. flywheel, 6KR,start full circle rear seal, 7KR, start roller lifter | 14 (356) |
| 4.3L | KP | 1988–1992 | 14 (356) |
| 4.3LX | KR | 1988–1992 | 14 (356) |
| 4.3L | XXG | 1985–1992, special service long block for engines with mechanical fuel pump. No intake,flywheel or balancer on long block. Can be used on 2 or 4 bbl engines. | |
**GM V6 262 cid (4.3L) Gen II with Electric Fuel Pump – Sterndrive Models (LH rotation), roller lifters
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 4.3L | KP | 1992–1993, 2KP, start electric fuel pump | 14 (356) |
| 4.3L | LJ | 1993–1996, 3LJ, start balance shaft models, 5LJ, start plasticfront cover | 14 (356) |
| 4.3LX | KR | 1992–1993, 2KR, start electric fuel pump | 14 (356) |
| 4.3LX | LK | 1993–1996, 3LK, start balance shaft models, 5LK, startplastic front cover | 14 (356) |
**GM V6 262 cid (4.3L) Gen+ – Sterndrive Models (LH rotation), roller lifters and rocker arms
| Model | GM Code | Comments | Flywheel Diameter in. (mm) |
| 4.3LX | LJ | 1996–1997, 6LJ start Gen+, GM 2–bbl intake | 14 (356) |
| 4.3LXH | LK | 1996–1997, 6LK start Gen+, GM 4–bbl intake | 14 (356) |
| 262 Mag EFI | LK | 1996–1997, 6LK start Gen+, GM 2–bbl intake | 14 (356) |
| 4.3L | LJ | 1998–2001, 9LJ, start metric fasteners, 0LJ, startroller rocker arms | 14 (356) |
| 4.3L | LB | 2002–UP, GM 2–bbl carb intake | 14 (356) |
| 4.3LH | LK | 1998–2001, 9LK, start metric fasteners, 0LK, startroller rocker arms | 14 (356) |
| 4.3L EFI | LK | 1998–2001, 9LK, start metric fasteners, 0LK, startroller rocker arms | 14 (356) |
| 4.3L MPI | LJ | 2002–UP, 2LJ, start GM IAFM (GMEFI) intake | 14 (356) |
Go Directly to the V6 Longblocks in the Store………V6 Marine Longblocks