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8 3/8 rear end?

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85crewcabbie

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I was looking at buying a drum to drum posi rear end for the posi and gear set for my '87 D100. The rear is out of a '78 D100. It seems (SEEMS is the key word) to have a differently shaped rear cover than my 8 1/4" and that confused me. Looked it up in the '78 shop manual and it said the rear was an 8 3/8" rear end in the '78. I've never heard of that and am wondering is there actually an 8 3/8" rear that is different from my later 8 1/4" rear of is it just a notational difference and they are in fact the same rears with parts that are interchangeable. Any help appreciated.
 
85crewcabbie said:
I was looking at buying a drum to drum posi rear end for the posi and gear set for my '87 D100. The rear is out of a '78 D100. It seems (SEEMS is the key word) to have a differently shaped rear cover than my 8 1/4" and that confused me. Looked it up in the '78 shop manual and it said the rear was an 8 3/8" rear end in the '78. I've never heard of that and am wondering is there actually an 8 3/8" rear that is different from my later 8 1/4" rear of is it just a notational difference and they are in fact the same rears with parts that are interchangeable. Any help appreciated.
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Was that by chance a factory service manual?
 
The 8 3/8 axle is what Mopar called an 8 1/4 in a van or pickup. (I have a theory on what might be different but need to have a few axles to take apart to test it). Everything inside is not just interchangable but is the same parts. The diff cover design has changed slightly over the years for all of the axles, perhaps due to axle assembly location? The big difference between those two axles is the bolt pattern, you'll need to swap your axle shafts and drums.
 
@captainchrysler - I am really buying the rear to get the posi and 3:55 gear set. At this yard it's cheaper to buy the whole thing drum to drum rather than just the gear set. As far as the gears and carrier go, if I understand you correctly these will work in my 8.25 rear because they are in fact 8.25 parts. Correct?

@7mopar - Sadly no it was a Clymers book that covers like 20 years. I did not have the factory manual for that specific year.
 
The ring gears maybe be slightly different. I know there is one the differential carrier pin can't be removed with the ring gear intact and one that can. I needed the pin only and the one I was trying to get the pin out of was not cooperating. A BFH took care of it and the pin went right into the one needing it. I thought it stupid at the time. Like why will not this pin come out.
 
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