Depending on the watch, you may want to have the 2846 repaired instead of replacing it with a more modern movement. Or, at least, in the case of something vintage, the 'slow beat' 2846 ticks at a speed that is closer to many gens from 25+ years ago. Or, you might want to find another 2846 instead of a modern replacement. Keep in mind, also, that unless you implant a new/freshly serviced movement, you may end up causing yourself more headaches. Mechanical watch movements generally require routine (every 5-7 years) overhauling (disassemble, clean, oil, adjust) & most rep watches come from the factory with used &/or unserviced movements. So your next movement may just be another ticking time-bomb in need of its routine overhaul.