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1970 mustang coupe diff identification.

Well it could be a different one from what it came stock. I’ve done some research and just got confused with how to identify a diff without a tag. At this point I thought I’d ask here how to figure out exactly what diff I have.

I post some pics in a bit
 

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So after reviewing a few websites and the one provided above i still can’t pinpoint exactly what the diff is.

I think I’m going to wise up and call a rear end rebuilding company and have them try and help me figure it out.
 

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What exactly are you trying to determine? Difference between an 8" and 9" is easy. Gear ratio is easy. Traction-Loc or not is easy. These things don't involve rocket science.
 

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Pics would help.
One of the nuts on the pumpkin on a 9 inch can only be gotten to with a wrench, not a socket. I forget which one but someone here will chime in.

You need to listen to these people and have a little bit of patience. Most of the people here are very knowledgeable about these cars and willing to help, but it is two way street.

Russ
 

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Thank you all for your concern. Yes I’m pretty sure it’s an 8 based on the casting number. From there on though is a mystery to me.

Based off all the info I have I can’t determine much else without disassembling the diff. Is that correct?
 

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Mark your driveshaft, put your rear on jack stands and rotate your rear tire one rotation with the car in neutral. Have someone watch the drive shaft. How many times did it rotate? This will give you a approximate rear gear ratio.
 

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Mark your driveshaft, put your rear on jack stands and rotate your rear tire one rotation with the car in neutral. Have someone watch the drive shaft. How many times did it rotate? This will give you a approximate rear gear ratio.
Haha well the drive shaft is off and I’m taking the rear off soon. I expect to disassemble the rear anyway.
 
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