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Just for the record, "OSGR" means OFFSET gear reduction.
"Offset Gear Reduction Starter (OSGR)
This type of starter uses an internal gear set used to increase torque. The internal gear sets are offset which means the drive gear and motor rotate on different axes."
"Planetary Gear Reduction Starter (PGR)
This type of starter is similar to the Offset Gear Reduction, however the gear sets are not offset which means the drive gear and motor rotate on the same axis."