While going through the service records from the former owner of my '90 740 B234F, I found an old dealership repair order (A/C system was serviced, and the exhaust manifold gasket was replaced) which includes notes regarding other conditions observed by the tech: "radiator seeps at upper neck, front shocks weak, timing belt cover broken, limiter missing, splash shield missing, minor oil leaks."

It's the only reference to a "limiter" I saw in the entire stack of records. Anyone know what it is?