I was on an older wayne oil burner and found the fuel pump seized. Pump is single stage and has no markings on it whatsoever. From my understanding, the older pumps are 1725 rpm. This one is direct drive. I also heard belt drive are mostly 1725 rpm. How do I know for sure whether to choose a 1725 or 3450 rpm pump if there is no written indication of what is required? I just don't want to assume. Thank You