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1967 - 1972 F-100 & Larger F-Series Trucks Discuss the Bumpsides Ford Truck

?? rear diff ??

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Old May 9, 2007 | 09:40 PM
  #1  
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f2501967
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?? rear diff ??

i have a 67 f-250, the tag on the rear says: C71A-DL. below it, it says: 602910 then a space 3.73.
what in the world does this all mean. i think DL=DETROIT LOCKER??
and 3.73 the gear ratio??
any and all help would be greatly appreciated. im currently running a re-built 390 with a .484 lift cam (edelbrock) along with the performer 390 intake and a holly 500cfm 2bbl. just trying to gain some gas mileage. also have a k-n filter with a tornado under it.
 
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Old May 10, 2007 | 03:31 AM
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Originally Posted by f2501967
i have a 67 f-250, the tag on the rear says: C71A-DL. SHOULD BE C7TA-DL below it, it says: 602910 then a space 3.73.
what in the world does this all mean. i think DL=DETROIT LOCKER?? No. DL is just the Ford engineering suffix (in this case) for C7TA.
and 3.73 the gear ratio??
any and all help would be greatly appreciated. im currently running a re-built 390 with a .484 lift cam (edelbrock) along with the performer 390 intake and a holly 500cfm 2bbl. just trying to gain some gas mileage. also have a k-n filter with a tornado under it.
C7TA-DL = Dana 60 / 3.73-1
 

Last edited by NumberDummy; May 10, 2007 at 03:34 AM.
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Old May 10, 2007 | 08:36 AM
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3.73...pretty common gear ration in the F250s of that vintage. I'd look for a 3.54 to swap in, that might help the mileage just a tad. Also. pull off that Tornado-thingy and toss it in trash. Those things actully disrupt the air flow and can hurt your mileage rather than help it. The only thing they have going for them is good marketing...
 
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Old May 10, 2007 | 10:03 PM
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tiger dan, that tornado does work, before it i was getting about 6-7mpg. after it im getting about 7-9mpg
 
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Old May 10, 2007 | 10:16 PM
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I can't help but be skeptical, the subject has come up many times here...do a search on the site for "Tornado" and see what many knowledgeable folks have to say about it. It's possible that your mileage increase could be due to other changes you made at the same time, possibly a tune up or new air filter, something like that. Like most vehicles, my '68 F250 is very sensitive to the way I drive, and I can vary the mileage by 3-5 mpg just by driving with a lead foot or eggshells...

But hey, if it works for you, then what the heck!
 
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Old May 10, 2007 | 10:46 PM
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tiger dan, i forgot to mention that i had the tornado for about 2yrs, before i had to rebuild the engine
 
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