New wiring connector (Pigtail) lead. Approx. 4" of lead. Connector is for 1977-1991 GM HEI distributors with internal ignition coil. Leads are for tachometer and power. This single connector with dual wires replaces the stock dual connector single wire pigtails for a tighter fit. Your cap cannot have the divider between the connectors for this to fit (most do not have the divider).  Fits the following:

77-86 V8 Camaro/Firebird w/ Factory HEI distributor
84-91 V8 Corvette w/ Factory HEI distributor