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Gear ratio question

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Old 02-04-2014, 06:53 PM
my 66 my 66 is offline
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Gear ratio question

I have a 65 f-100 with a 302 with a mild cam. The truck has a 5 spd out of a 95 f-150 I-6. I have the rearend out of the truck the trans came out of and i want to put it in the truck. The tag on the rearend has S842A
73 88 1A09
Can someone tell me the ratio of this rearend?
Also has anyone had this setup are close to it and how did it work? I will pull a car trailer now and then and i would like to know if it will do the job?
Thanks for any help you can give.
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Old 02-04-2014, 07:35 PM
norfolknova norfolknova is offline
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It looks like you are missing a digit, but from what you posted it looks like a 3.73 gear with an 8.8 inch ring gear made in 1991?? january 9th

I found this using google

Differential Identification | West Coast Differentials

You should do o.k. towing with that combo

matt
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Old 02-04-2014, 08:00 PM
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OBS trucks never came with 3.73 gears from the factory. I think we need more tag numbers.
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Old 02-04-2014, 09:03 PM
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Thanks

Thanks for the replys i will recheck the tag tomorrow and she if i can see the missing number and let ya'll know. Thanks Don
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Old 02-04-2014, 11:03 PM
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most likely 2.73
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Old 02-05-2014, 09:05 AM
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most likely 2.73
X2
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Old 02-05-2014, 09:48 AM
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checked the tag this morning and their is a 2 next to the bolt which makes it a 2.73 ratio. So with my 302 how will it be suited for pulling a car trailer now and then. I looked on the west coast site and it stated small block should turn 1800, to 2800 rpms at highway speed. so is highway speed 55, 60,65or70 mph. The site said 2.73 with 235-75-r15 at 70mph it will turn about 1779 rpms. What do ya'll think?
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Old 02-05-2014, 09:51 AM
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No way would I ever consider a 2.73 gear ratio in any truck. 3.55 or better is my recommendation. Why Ford ever put such a tall gear in a truck is beyond me.
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Old 02-05-2014, 10:42 AM
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This should say it all, the factory tow rating for an I6 truck with manual trans and 2.73 gears was ZERO. Go find yourself a 3.55LS axle.. it was very common in 5.0 and 5.8 1/2 ton trucks.
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Old 02-05-2014, 11:26 AM
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Originally Posted by Conanski View Post
This should say it all, the factory tow rating for an I6 truck with manual trans and 2.73 gears was ZERO.
I think it was actually zero to 2100 lbs

The 3.55 with bring that up to 3600.
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Old 02-05-2014, 05:05 PM
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Ok we not putting the 2.73 rear in the truck. Now, the tag on the stock rear reads BG-f2 3.89 3MG 301. I think this tells me its a 3.89 ratio rear which should pull my trailer fine. So if i rebuild my stock 9" rear with the 3.89 i would like to get another chunk and put some taller gears for when i'am around home in south louisiana (flat) and not pulling are carrying a load. Would 2.73 be ok with my 302 mild cam 5 spd?
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Old 02-05-2014, 06:45 PM
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Originally Posted by my 66 View Post
Ok we not putting the 2.73 rear in the truck. Now, the tag on the stock rear reads BG-f2 3.89 3MG 301. I think this tells me its a 3.89 ratio rear which should pull my trailer fine. So if i rebuild my stock 9" rear with the 3.89 i would like to get another chunk and put some taller gears for when i'am around home in south louisiana (flat) and not pulling are carrying a load. Would 2.73 be ok with my 302 mild cam 5 spd?
See my answer in Post# 8: Ford Truck Enthusiasts Forums - View Single Post - Gear ratio question

That 302 needs RPM to build some torque. Add in a "mild cam" now your power curve is shifted to the right versus a stock 302. That means it may makes less torque for the same RPM in the lower RPM range. Stick to the 3.89 geared 9" and call it day.
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