Thread: 9" axle I.D.

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I want to run my brake lines before I get my body on the frame and I need a new pinion seal so I have to figure out what I got.

I was sure it was an '86 F150 with 3:50 gearing but the seal I bought didn't fit so before I go and get mad at the parts guy I want to make sure. It has a bunch of numbers on the third member but I couldn't find any on the actual axle:

S318D

3 50 9 5A16

E3TWBA

3074

What the heck does it all mean?????

Sean

I've read that some of the mid-80's used a seal from an 8.8 diff.

5a16 i think is January 16th 1985 almost sure but do a search of kevin stang

Maybe this will help

http://www.kevinstang.com/Ninecase.htm

Pat

I'll have to measure that seal diameter but that was really helpful. I'll have to go out and take a real close look but from my pictures I think I can figure it out. The tag seems to mean it's a 3:50 with a 9" ring gear, the pinion support and the case both point toward a standard 9" with the fill plug, the housing ends look like large bearings and the end of the spline shaft look like 31 spline. No posi is a good thing for me as well.

Thanks a lot guys,

Sean

yep the 3 50 9 is a 3.5 -1 ratio good numbers also and a open 9 inch gear .