7.5 or 8.8

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Jul 19, 2004 | 10:57 PM

asauppee

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7.5 or 8.8

Ok i know that on the tagon the rear end it will give you the gear ratio but dose it also give you the size. I need to know what size differentiali need for my 1991 f250. It currently has an open rear and i want ot go limited slip but dont know the size. any suggestions?

Jul 19, 2004 | 11:00 PM

Saurian

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From: Centerville, Iowa

Did 7.5's even make their way into full size trucks? I think the question you should be asking is whether you have an 8.8, 9, 10.25, or Dana 60. Look at the code in the door jam, and then at your owners manual. Or else give us the code, I'll tell you eventually hehe.

Jul 19, 2004 | 11:21 PM

SoCalDesertRider

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'91 F250 should have the 10.25" Ford axle with 8-lug 16" wheels. It could be full-float or possibly semi-float (not sure when they started with that semi-float 3/4-ton business). Either way, the 10.25" axle has 12 cover bolts and the cover is shaped a little like a Dana axle, but not quite. If your truck has a GVWR of around 8600 lbs or more, it should be a full-float 10.25". You can tell if it is full-float by looking at the center of the wheel. If there's a hub sticking out there with bolts around it, it's a full-float. If all you see is the flat end of the axleshaft, it's a semi-float.

Last year for the 9" axle was around '84 and it was a half-ton axle, not used in F250's. Dana 60's were last used in the rear of F250's around the late '70's, maybe into the early '80's. The 8.8" axle is in F150's and Broncos, typically.

Jul 20, 2004 | 09:00 AM

Saurian

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From: Centerville, Iowa

D60 till 84, 10.25 after that.

I just didn't think the 7.5 ever made it up to fullsize (thankfully).

Jul 20, 2004 | 12:06 PM

Boss_358

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7.5 axles are barely even in Rangers any more. Only in the 2wd one as far as I know. I had a friend that used to have an 84 or 85 F-250 diesel that had a Dana 60 rear.

Jul 20, 2004 | 04:07 PM

asauppee

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10.25

ok thanks alot for the info. I havent; worked much with rear ends so i didn;t know what would be in it. If its is a 10.25 where can i get a limited slip differential for it since all i've been finding on summit and like sites is 8.8in and 9in.?