Apparatuses, methods, and systems are disclosed for supporting a mixture of BR and HFBT. One apparatus (600) includes a processor (605) that provides a physical ("PHY") layer (255) and a Medium Access Control ("MAC") layer (260) and a transceiver (625) that communicates on a sidelink channel. The processor (605) determines (805) a minimum time duration between a first resource for HARQ transmission of the transport block ("TB") and a second resource for HARQ transmission of the TB. Here, the minimum time duration comprises a sum of: a first time to receive HARQ feedback, a second time to determine whether to perform retransmissions of the TB, and a third time to retransmit the TB. The processor (605) selects (810) a retransmission mode based on the minimum time duration and selects (815) sidelink resources for retransmission of the TB based on the selected retransmission mode.