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Old Jul 5, 2004 | 12:20 PM
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Differential tag

99 F150, 4X4, SC, auto: How do I decifer the tag ,and I need a cover gasket, my parts store says it lists only one for 12 hole cover. The gasket is right design but a bit too large.Is there something more to go by?? I need to change an axle bearing. Thanks
 
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Old Jul 5, 2004 | 04:09 PM
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somewhere on there it will have something like 8 8 for an 8.8 rear, or 9 75 for a 9.75 rearend.
 
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Old Jul 5, 2004 | 04:48 PM
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The second line of the axle tag will give you the ratio in a three or four digit alpha numeric code (3 55 or 3L55 the 3 is usually under the bolt) then the ring gear size. If the parts store doesn't go by ring gear size I'd be nervous.

-Kerry
 
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Old Jul 5, 2004 | 06:52 PM
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Thanks, it"s a 3.55, with a 9.75 gear.
 
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Old Jul 5, 2004 | 07:36 PM
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gfreek did you find a gasket for it?
From the factory they just use silicone with no gasket.
 
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Old Jul 5, 2004 | 09:00 PM
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No I did not, checked 2 parts stores, they list 2 gaskets, 12 or 10 hole, mine is a 12 but different size, so I'll have to use silicone I guess. What silicone would you recommend ?
 
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Old Jul 5, 2004 | 11:05 PM
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I like Permatex Ultra Blue, Black or Copper. They all seem to work well.
 
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Old Jul 6, 2004 | 12:54 AM
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So mine says L55 88 6F07. (Wrote this down before I saw thread and didn't realize that there may be a # under bolt.) So I am assuming that I have Limeted Slip 3.55 with 8.8 gear? What do the rest of the # mean?
 
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Old Jul 6, 2004 | 06:08 AM
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Thanks Racerguy, I'll do the silicone thing. Axle bearing is just starting to get some play so I figured I'd tackle it before it got worse, plus it's boat towing season. So thanks again.
 
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Old Jul 6, 2004 | 08:18 AM
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Tony you're right about it being an 8.8 with 3.55 LS.
The 6F07 is a build date code. It looks like it was built in 1996, F= 6th month, 7th day.
 
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Old Jul 6, 2004 | 04:07 PM
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Anything tips I need to know before tackling this? It seems pretty cut and dry from the manual, when you pull the pin partially out of the differential, does the side gear fall out of place??
 
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Old Jul 6, 2004 | 06:54 PM
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Thanks Dave! Never would have guessed about the build date.

gfreek ... sorry for butting in on your thread.
 
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Old Jul 6, 2004 | 06:54 PM
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As long as you dont rotate the axles while the cross shaft (pinion shaft) is out the side gears and spider gears (pinion gears) should stay in ok.
 
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Old Jul 6, 2004 | 10:12 PM
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97Centurion,FelPro makes a 8.8 differential gasket.It is part # ;
FelPro RDS-55431
I get mine at Advance auto parts.They will most likely ask you the year application,then say it dont call for a gasket.Just give them that part # ; it fits all 8.8 differentials.
 
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Old Jul 6, 2004 | 10:46 PM
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Cool, I was thinking about changing my Diff fluid to some fresh stuff. Thanks!
 
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