1971 ford ltd 351w

Is there anyway to visually tell the difference between a 71 and 72 detuned engine. I recently bought this car thinking it had the 240 hp engine but when I went to get a new air cleaner, the 71 cleaner was too
big (thats what the autozone computer called for). the air cleaner for 72 fit. which engine do I have? thanks for any help.
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I thought the biggest difference between a '71 and '72 351W was how they rated the engines - gross HP in '72, Net HP in 72. Otherwise I don't think the actual power output was much diffrent.
Ed
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thanks ed, the autozone man tried to explain that to me. it says on the air cleaner "regular gas" but wasnt regular gas a higher octane back then? my son thinks I should use midgrade at least.
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On Thu, 15 Sep 2005 00:54:45 -0400, snipped-for-privacy@webtv.net (Peter Gennuso) wrote:

No. The octane ratings for all grades was the same then and now. They changed the display on the pumps by using the average of the research and motor octane ratings. If it was a regular fuel engine before, it is still a regular fuel engine. If the engine has collected a bit too much carbon over the years, it may be experiencing what is commonly called octane creep such that it will need a step higher octane gasoline to prevent detonation or "ping". That said, a little "ping" is not bad for an engine as it can help reduce the rate of carbon buildup. A slight "ping" of short duration is also one indicator that the engine is near optimized for best performance and fuel economy.
Lugnut
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