Call me stupid! I.D. 8 & 3/4

I have a few stupid questions. To make a long story short if you can veiw my restoration project under " 74 Dart Sport ( Hang 10).
I know the rear end on my car is not the original. What I don't quite know is what it came from. I'm sure it is an 8 & 3/4. It has a 489 case. Is it safe to say the axle housing is also from a dodge? I am not very knowledgeable about this subject.
I know the 8 & 3/4 is very desirable. Is there any reason why I should'nt keep this on my car? I'm not sure why a preveous owner would replace only the rear end as the rest of the car was very original.
My car has always performed well & I don't think their is any problem but I want to get some other opinions.

I know they changed the bolt pattern but I don't know if there is an advantage to having large bolt or small bolt or how to tell the difference for that matter.


I have been looking at several mopar mags but no one really goes into depth about this subject. I know I need to learn a lot more about the rear end but I hope some of you can answer some of my questions. Thanks, Steve.
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I thought when I got the chrome rims put on they were the ones that put the spacers on but it was about ten years ago & I don't recall. I think the two ralley rims that came on the car were on the rear.
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