GM Gen III V-8 Cylinder Head Comparison - Gen III Tech
Which Cylinder Heads Offer The Most Power Potential?
Photography by Will Handzel
| Gen III Cylinder Head Casting, Machined and Final Part Numbers |
| RPO | Size | Part Numbers | |
| Year | Casting | Machined | Final Assembly |
| LS1 |
| '97-'98 | 10215339 | 10215339 | 10215337 |
| 12558806 | 12558806 | 12558808 |
| '99-'01 | 12559853 | 12559854 | 12559856 |
| '01-'04 | 12564241 | 12559854 | 12559856 |
| 12559853 | 12564242 |
| LS6 |
| 01-04 | 12564243 | 12560800 | 12560802 |
| | | 12569315 |
| | | 12564824 |
| LQ9 |
| '02-'04 | 12562317 | 12562318 | 12565363 |
| LQ4 |
| '99-'00 | 12581873 | 12561874 | 12561876 |
| '01 | 12562317 | 12562318 | 12562320 |
| '02-'04 | 12562317 | 12562318 | 12565363 |
| | | 12565364* |
| LM4, LM7 |
| LR4, L59 |
| '99-'01 | 12559862 | 12559863 | 12559865 |
| '01-'04 | 12561706 | 12561708 | 12563678 |
| 12569862 | 12559863 |
| *(this PN also good for RPO KL5; the natural gas engine) |
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