This is a NEW never USED MSD 2 Step part # 8739.
MSD Ignition 8739 2-Step Module Selector For Use with:
MSD 87311 2-Step Rev Limiter, 2/23/2016 - Newer Except DI 5.0L
MSD Ignition 2 Step Launch Control GM LS Engines 8733
MSD 8732 2-Step Rev Control for Digital 6AL, PN 6425 or 64253 only
MSD 8734 2-STEP Launch Master