The M57 (or any probe start ballast) is a two-component ballast, transformer and capacitor. The M137 (or any pulse start) is a three component ballast, transformer, capacitor, and ignitor. The ignitor looks a little like a second capacitor, but it's basically a totally different component.
Odds are not all that bad that the M59's will suit you fine for the moment. If the bulbs flicker or don't start up, then something's amiss but if not and you're happy ... then no worries.
