It's a relay, good size, 311 906 063B mounted next to the pressure sensor on a 73 Thanks Keith Top Notch Restorations topnotch at nycap.rr.com http://www.a383ina68.addr.com/radiorest/main.htm 71 Squareback "Hothe" 65 Notchback "El Baja Rojo" 65 Squareback "Eggcrate" 87 golf "Winterat" 93 RX7 "Redstur"