A replacement starting motor of the type for use in starting a passenger vehicle internal combustion engine is provided by converting a donor motor originally manufactured for one engine installation into a form making it a substitute for a starting motor manufactured for a different engine installation. The motor shell and solenoid housing and internal features contained therein are retained as a core from the donor starting motor in the replacement starting motor. A newly developed end cap assembly having a shape and spacial dimensions enabling the retained components of the donor starting motor to fit the different engine installation of the starting motor being replaced is attached to the donor core. A newly developed pinion sleeve having a unique length dimension is provided in the replacement starting motor to enable the retained components of the donor starter to properly bring the drive pinion into and out of driving engagement with the flywheel associated with the different engine installation. The armature shaft of the donor starting motor is length-adjusted to enable the replacement starter to fit the spacial requirements of the different engine installation.