While the torque monster W-code L75 455 vanished after the '76 model year, this '78 has the base Z-code 180-horse Pontiac 400. An optional W72 400 delivered 220 hp. The bummer is that both 400s carried engine code Z in the fifth digit of the VIN. Look for the stamped block code WC or X7 to verify hot-dog W72 status. Of the 187,285 Firebirds built in 1978, 93,641-just under half-were Trans Ams.