Sierra 18-5438 Ignition Coil for Thunderbolt MerCruiser & Crusader IgnitionsSierra replacement ignition coil. All Sierra aftermarket parts are manufactured to meet or exceed OEM requirements.Fits: GM V-6 & V-8 Engines With HEI Thunderbolt IV & V Ignition; Features: Primary Resistance: 1.0A 15 ohms; Secondary Resistance: 8KA 20 ohms; Shape: Cannister; Input Voltage: 14+0.5V; Output Voltage: MIN16.5KV; Primary Resistance Tolerance: +15%; Secondary Resistance Tolerance: +15%; Primary Inductance: 7.85mH+20%; Secondary Inductance: 36.8H+20%; Interchangeable with: CDI; E18-0008; Crusader; 37068; Mallory; 9-29701; MerCruiser Stern Drive; 300-8M0079202; 392-7803; 392-7803A4; 392-805570A1; 392-805570A2;