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7.5/7.625" rear differences


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I have an 87 Salon with an open 2.56 rear. That ratio's gotta go. I found an 84 GP in a junkyard with a 3.23 posi that would be great, but the junkyard guy is a waste of space and refused to sell me just the center section and he wanted $200 for a mangled axle. I can get a new eaton posi for $300 and told him (tactfully) to blow it out his ear.<P>In my search (junkyards, ebay, summit, etc) I've seen many 7.625" posi units, but passed them over because of the 28 spline axles required. In the Eaton description of the 7.625" posi center, they say that it can be used in a 7.5 axle if you use 28-spline axles. I know that a good source for 28 spline 7.625" parts are late model F-bodies.<P>- How long are F-body axle shafts?<BR>- are they suggesting using F-body shafts?<BR>- Right now at the summit outlet in OH, they have a 7.5/7.625" posi for $300 (marked down from $429).<P>Here's the quandry: I want one of the ratios like 3.23/3.42/3.73 and really want a posi. I found the 3.23s in the junkyard, but need to pass that up for obvious reasons. Before I pass up any more cheap 7.625" rears, how easy is it to use one?<P>Curtis

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  • 2 weeks later...

A few years ago ,a friend set up a posi unit out of an S-10 truck, and put it in the rearend of a 79 Malibu. <BR>It lived for a while behind a high 12,low 13 second big block Chevy.<BR>I'm going to try it myself in an 84 Cutlass with a 68 400 Olds.<BR>Good Luck

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  • 3 weeks later...

Curtis,<P>If you can afford it go with a Grand National 8.5" rear end. It will drop in with no modifications and is much stronger than the 7.5 or 7.625 rear ends. They were available in both 3:42 and 3:72 ratios and have posi.

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  • 5 weeks later...

The 7.625 really isn't that bad of a rear if your staying 300hp or lower, the monte ss 7.625 had a 3.42 r+p matched up w/ the th-350(83-84ss) and a 3.73 matched up w/the 200-r4(85-88ss). If you have the money the 8.5 is much stronger and can be found is the gn and the 442 but if your salon had a 7.5 you'll have to shorten your driveshaft by .99"

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