7.5 to 8.5 wheres all the threads for this swap?

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kingrichard

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Aug 24, 2014
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1985 cutlass, what cars have the 8.5 that will bolt right in? whats the width on the 7.5 and 8.5?
 

oldtinsmith

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Jun 14, 2010
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Buick T-type and GN's, 1984 & up Hurst Olds and 1985-87 Olds 442's IIRC, the only thing different for a complete bolt in is the drive shaft. The drive shaft used with the 8.5 rear in a G-body is 1 inch shorter than the 7.5 rear drive shaft.

Doug
 

pontiacgp

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Mar 31, 2006
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kingrichard said:
pontiacgp said:
what rear end from the 60's and 70's are you thinking of?
anything better that a 7.5.

there is 8.2 and 8.875 rear ends from those years that fit the G body with conversion uppers. The 64 - 67 A body rears is 2.5" wider than the G body rear and the 68 - 72 A body rear is 4.5" wider than the G body rear
 

kingrichard

Not-quite-so-new-guy
Aug 24, 2014
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pontiacgp said:
kingrichard said:
pontiacgp said:
what rear end from the 60's and 70's are you thinking of?
anything better that a 7.5.

there is 8.2 and 8.875 rear ends from those years that fit the G body with conversion uppers. The 64 - 67 A body rears is 2.5" wider than the G body rear and the 68 - 72 A body rear is 4.5" wider than the G body rear
this what im looking for, thanks man.
any info useful.
 

pontiacgp

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Mar 31, 2006
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Kitchener, Ontario
another thing I thought of is the lower control arm on the 64-67 rear ends doesn't fit due tot the location of the bracket on the rear end is closer to the center than on a 7.5 even though the 64-67 rear end is 2.5" wider. I have an 8.2 from a 67 Chevelle and had UMI make me a custom lower with the roto joint that took up the discrepancy. I suggest you go with UMI parts as they are great to deal with and are a contributor here.

Lower%2520axle1.jpg
 

marcar1993

G-Body Guru
Aug 31, 2007
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