9" rear end Help

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Feb 20, 2011 | 01:22 PM

sitdog84

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5th Wheeling

Joined: Nov 2010

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9" rear end Help

I have a 67 F100 that I pulled out the 460/C-6 combo. It has a 3.25 rear diff. I put in a 300 I-6 with a 4speed out of a 85 F150. Can I just swap out the 3rd member out of a 70 F100 that has 3.70 gears. Basiclly this 3rd member has 10 teeth vice 12 which would make it a 3.90. Any advice??

Feb 20, 2011 | 02:03 PM

lizardman1

Laughing Gas

Joined: Jul 2007

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From: Phoenix

Yes you can do that, just double ck the tooth count for the gears and the spline count for the axles.

Feb 20, 2011 | 02:08 PM

frankensteined_67

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From: salt lake

as long as the axle splines are the same then yes. or you could just swap out the ring and pinon gear from the 3rd member's.

Feb 20, 2011 | 02:23 PM

sitdog84

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5th Wheeling

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So i understand you all, I can take the 10 tooth pinion gear that was matched with a 37 tooth ring gear and put in to a rear end that has a 39 tooth ring gear.

Feb 20, 2011 | 04:20 PM

frankensteined_67

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From: salt lake

yes you can. the 3rd members bolt in the same in every 9in. you just have to make sure that the axle splines are the same. you should have 28 splines on both but you should verify that they do.

Feb 20, 2011 | 05:50 PM

ilovemy60ford

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I've not ever heard of this - I think that ring and pinions are matched, right?

I wouldn't think mixing rings with the same pinion would be good, but I will defer to any one who knows for sure.

You can mix whole center sections (3rd members), sure...but not rings and pinions.

Feb 20, 2011 | 05:52 PM

60F100

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Joined: Nov 2003

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From: Cantonment, Fl

Quote:

Originally Posted by sitdog84

So i understand you all, I can take the 10 tooth pinion gear that was matched with a 37 tooth ring gear and put in to a rear end that has a 39 tooth ring gear.

I do not believe you can. Ring and pinion gears come as matched sets. You can take one 9 inch pumpkin and put in another housing as long as you have the proper axels. Most of the early 9 inch rearends had 28 spline axels and a lot of the later ones had 31 spline axels.