Ok I had a look around for this error:
| Error Code: SMPA60 |
Meaning: Unrecoverable fault - Please restart the game
Its not your fault, its the fault of the person who created the model and didn't update it with mesh deformation.
Here is a direct quote from ZModeler forums:
| Fatal Error SMPA60 was confirmed to appear on models with missing objects. You need to keep the same "extra_*" objects and passanger seat dummies as in original vehicle. At least a complete replace of schafter model does not cause SMPA60 error when missing "extras" were added. |
Mesh deformation was updated. Exported models should have the same level of visual damage as original models. You should re-export your models to get them updated.
I suggest you back up your original GTA IV models before you replace them with mods.