Steel Hood vs Alluminum Hood

I was wondering how many pounds lighter is the alluminum hood from the steel hood???

 

1987 Turbo II stock steel hood: used, windshield spray nozzles and hoses attached, all underhood insulation and front rubber flaps attached, 5A blue paint = 51.80 lbs
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1987 Turbo II stock aluminum hood: used, NO windshield spray nozzles or hoses, all underhood insulation and front rubber flaps attached, hood stripped (NO primer base) and repainted yellow = 29.20 lbs

---http://www.fc3spro.com/TECH/

 

Thanks