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Discussion Starter #1
I was ordering my 3.50 gear today and the guy from Summit wanted to know what size bearings I needed for my Rebuild kit. I have no idea I tell him. I know it is a 9" from a 69 Mach 1, open rear, 28- spline. He still says I need to tell him the bearing size.

Does any one know, short of taking the thing apart, which one or what he is talking about?

Thanks
 

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I know there are 3 different bearing sizes but I couldn't tell you by application either. The only person I think would know this off the top of his head would be DENVER on this forum. Do a search for his user name or PM him?

The other problem with doing it by application is that you are dealing with a 30 year old car. The possibility exists that the whole center section has been changed before and may or may not be the same bearing size as the original application.
 

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Here is a well researched page on the Ford 9". If you cann't find what you need on the page perhaps the page author can help. http://www.ultrastang.com/Rearinfo.asp?Page_ID=1
Here is a specific quote from that page that looks like an answer to your question. "The axle housing's bearing size can be determined (as to whether they are of the large bearing type or the medium bearing type) by looking at the holes in the housing's end flanges where the drum brake backing plates bolt up. The large bearing housings can be identified by the presence of (4) ½" backing plate bolts, while the medium bearing housings can be identified by the presence of (4) 3/8" backing plate bolts.
The ½" backing plate bolts will require the use of a ¾" socket to break the (4) backing plate retaining nuts loose with, while the 3/8" backing plate nuts will require a 9/16" socket."
HTH
 

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See if the info below makes any sense to the guy...

Differential carrier bearing, small (2)(coned roller) " # LM 102949
Differential carrier bearing, small(2)( outer race) " # LM 102910

Dollars to donuts you have the small bearing differential carrier...

The corresponding housing ID will be 2.890" and the OD of the differential carrier will be 1.781"

There is a larger bearing carrier but it is generally used with 31 spline units. I have such a unit in the race car. If you have such an animal, I can get you those bearing numbers as well.

Hope that helps!
 

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Discussion Starter #5
The guy tried to get me to buy both kits. I was thinking about buying the small one and taking it to my rebuilder. If it did not work then returning it and getting the larger set. I feel more comfortable about the smaller one now.

Thanks,
THomas
 

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Most of the 69 9 inchers I have come across have had the large bearings. Not that this is writen in stone! Ford did some goofy things in production over the years! Denver
 
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