An ideal interactive 3D tele-immersion (3DTI) system is expected to disseminate and synchronize multi-streams with a shortest-possible latency among participating sites, achieve inter-stream synchronization, and bound both inter-sender and inter-receiver skews. This is, however, a key challenge because of (1) the coexistence of multi-modal, correlated, bandwidth-savvy streams from multiple source media, (2) the bounded bandwidth resources at each site, (3) the heterogeneous transmission end-to-end delays (EED) between sites and (4) the diversity of 3D views requested by multiple users. Our study of the existing content dissemination topologies reveals their inadequacy of handlings the complication and dynamics present in 3DTI systems. In this paper, we propose SyncCast, a multi-stream multicast dissemination scheme that takes into account the bandwidth constraint, as well as the inter-stream, inter-sender and inter-receiver synchronization. We classify the 3DTI media streams into different service classes based on the users' visual interests. SyncCast is designed to address the interactions among EED, synchronization and bandwidth in the real-world Internet settings. We compare SyncCast and our previous ViewCast algorithm. The simulation results show the improvement in the synchronization performance and the implementation feasibility of SyncCast in supporting the multi-site interactive 3DTI system.