Bear in mind that while this is technically allowed, finding a residency that is actually amenable to it is a higher hurdle. Most if the shared residency stories I have seen involved folks already in residency that a PD didn't want to lose, rather than folks initially matching. It creates more administrative hurdles for PDs than simply filling the residency with full timers, so places that easily fill aren't going to jump at the shared residency option. You can look, but I sure wouldn't bank on this being an option.