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Re: 1957-68 8's ('742' cases) interchanges

From: Joe Mac
Date: February 18, 2002


From what I've seen on this subject, the 489 should work in your '65 rear with the original axles. The yoke on the 489 will probably be the larger 7290 series. You can get an adapter u-joint to mate the smaller 7260 size on the driveshaft with the 7290 on the 489 pinion. The problem I believe comes from trying to install any case (741, 742 or 489) made after '64 into a '63 or older open differential rear. The axles in the early open rears are shorter due to a thicker thrust block in the carrier. Early sure-grips used a thinner thrust block which became the standard in '64. I don't beleive that the end-play shims can be changed to compensate for this difference. If you've got an early sure-grip, any center section should work. I've never seen or heard of a documented case where '65 or later flanged axles were installed in a Forward Look era tapered axle housing. I have seen this performed on an early a-body with a brake conversion so it's possible (not withstanding the above). Has anyone out there done this on a full size forward look car without shortening and resplining axles? If so, what was the donor car?


Last changed: July 19, 2018