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  •  » Interpret 9" rear end tag ?

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    9/05/2018 7:18 PM  #1

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
    Posts: 12,305

    Interpret 9" rear end tag ?

    Can someone tell what all the numbers mean on this tag?  It is in my 56 F100.

    WFC-G    6MA
    3L00   9   870A

    I know the 3L00 means 3.00:1 ratio and the 9 most likely means 9".
    How do you read the date and car type?  It is a 31 spline and the axle tubes are tapered to a smaller size and it has small bearings.

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
     

    9/05/2018 9:18 PM  #2

    josh-kebob
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    From: Madison, AL
    Registered: 4/06/2013
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    Re: Interpret 9" rear end tag ?

    steve,
    WFC-G is the rear assmebly for 69 Comet, 69-70 Fairlane, 69 Montego w/ a 3:00, 9" locking diff with 31 spline axles.
    870A is the plant code and I can't find anything on that.....best I can do so far
    Info found via fordification website.......
     

    Last edited by josh-kebob (9/05/2018 9:19 PM)

     

    9/06/2018 2:31 PM  #3

    Greg B
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    Re: Interpret 9" rear end tag ?

    WFCG = 69 Comet, 69/70 Farlane 70 Montego.  
    6MA  =  year 1968 month M December A=day 1.  so built December 1, 1968.   

    3L00 =  3.00 trac loc or tracker  4 spider 31 spline ( used in combination with the WFCG code. 
    9  =      9" ring gear
    870A is the plant code, but I cant figure it out.  A most likely means day shift.

    If multiple things can go wrong, the one that will go wrong will be the one that causes the most damage.
     

    9/06/2018 5:07 PM  #4

    MS
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    From: Canyon Lake, Texas
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    Re: Interpret 9" rear end tag ?

    Thanks!

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
       •Thread Starter
     

    9/10/2018 10:26 AM  #5

    Huskinhano
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    Registered: 4/26/2017
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    Re: Interpret 9" rear end tag ?

    If the center of the axle flange between the studs has a bathtub depression they’re 28 spline. All 31 spline axles have 3 dots but not all 3 dot axles are 31 spline, they could be 28 spline.

    I'm not a complete idiot.....pieces are missing. Tom
     

    9/10/2018 5:41 PM  #6

    red351
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    From: Carlisle, PA
    Registered: 5/31/2018
    Posts: 445

    Re: Interpret 9" rear end tag ?

    Huskinhano wrote:

    If the center of the axle flange between the studs has a bathtub depression they’re 28 spline. All 31 spline axles have 3 dots but not all 3 dot axles are 31 spline, they could be 28 spline.

    That's not completely true, as I have axles that are large (bathtub) for 31 spline, but machined down to 28 spline on the ends

     

    9/10/2018 8:11 PM  #7

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
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    Re: Interpret 9" rear end tag ?

    Definitely 31 spline.  I took it apart to install new seal sleeves, bearings and 2-18 Mustang disc brakes/

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
       •Thread Starter
     

    9/12/2018 6:56 AM  #8

    ultrastang
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    From: Camden, Arkansas
    Registered: 4/01/2013
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    Re: Interpret 9" rear end tag ?

    When these rear ends were being built, Ford didn't narrow the date of the rear end down to the day of production/assembly. In the string "6MA," "6" would be the year, "M" would be the month and "A" would be within the week of the month the part was assembled --"A" being the 1st week, "B" the 2nd week, "C" the 3rd week, "D" the 4th week and "E" the 5th week.

    If the 3rd member was for a '69/'70 model car, the "6MA" doesn't really make sense. "6" would represent the year (although this doesn't indicate the decade).  Are you sure the "6" isn't actually an "8"? (I can't clearly see the number in the photo).

     

    9/12/2018 12:40 PM  #9

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
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    Re: Interpret 9" rear end tag ?

    ultrastang wrote:

    When these rear ends were being built, Ford didn't narrow the date of the rear end down to the day of production/assembly. In the string "6MA," "6" would be the year, "M" would be the month and "A" would be within the week of the month the part was assembled --"A" being the 1st week, "B" the 2nd week, "C" the 3rd week, "D" the 4th week and "E" the 5th week.

    If the 3rd member was for a '69/'70 model car, the "6MA" doesn't really make sense. "6" would represent the year (although this doesn't indicate the decade). Are you sure the "6" isn't actually an "8"? (I can't clearly see the number in the photo).

    Good call, ultra.  I went back and looked at all my pics of the tag and it is, indeed, an 8.

    Rotating the wheels (both sides traveling equally in same direction, I am getting about 3.70:1 ratio, so somebody must have "been in there" before.
     

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
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    9/12/2018 1:36 PM  #10

    HudginJ3
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    From: Cedar Hill, TX
    Registered: 4/29/2015
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    Re: Interpret 9" rear end tag ?

    https://www.fordification.com/tech/rearends_ford06.htm
    https://www.fordification.com/tech/datecodes.htm
    https://www.fordmuscle.com/archives/2002/02/nineinch/index3.php

    These places helped me when I was building my diff. Mine is a WES-AA.

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