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Swapping diffs

Discussion in '6.9L IH & 7.3L IDI Diesels' started by BRShirk, Nov 9, 2019.

  1. BRShirk

    BRShirk Registered User

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    I just picked up a 93 F350 4dr longbed 4wd with a 7.3 IDI with a bad yoke on the rear diff.

    I dont have tools to change the yoke but I have a rear from a 91 F250 IDI. My Google-Fu is weak and cant find information on what rears were in these trucks.

    Good swap or get a boneyard F350 rear? And any tips on identifying the diffs to get new gears, F350 has 4.56ish and F250 has 4.11ish? I'm thinking 3.80s-ish so can keep upon I85..lol.
     
    Last edited: Nov 9, 2019
  2. Garbage_Mechan

    Garbage_Mechan Garbage Mechanic

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    Is your F350 single or dual rear wheels? If single a 87-97 F250 axle will fit. Unless some idiot left it off there is a tag with diff ratio on the cover bolts. 4.11 and 3.55 are the usual ratio choices in that year range.
     
  3. BRShirk

    BRShirk Registered User

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    Ok, great. 3.55s sound good. Are there any links to ID which diffe I have?

    Both are single axle. I was going to build the 91, it's a F250 extend 4wd 7.3IDI with ZF5 that needs head gaskets but I think it'll be a parts truck.
     
  4. 79jasper

    79jasper Chickenhawk

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    I've seen them rust off. Lol


    The 350 should have a D60 up front, 10.25 rear.
    You can look at the door tag too. That can be decoded. But the 250 likely has a ttb up front, 10.25 rear.

    Sent from my SM-N960U using Tapatalk
     
  5. Garbage_Mechan

    Garbage_Mechan Garbage Mechanic

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    LOL California natives have a hard time remembering things rust off.....
     
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  6. chillman88

    chillman88 Supporting Member Supporting Member

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    I was trying to ID a transfer case one time, nobody could understand that the tag wasn't there anymore, either that or it was rotted beyond legibility. I can't remember which but people that have never REALLY seen RUST make me laugh.
     
  7. snicklas

    snicklas 6.0 and Loving It!! Staff Member

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    Or the "Wow, that bolt came out a lot easier than I expected". You know the bolt that when you "sit down" to work on it you take all the tools you think you need so you don't have to get back up. You know, the correct wrench, socket, next smaller socket, vice grips, hammer, "favorite spray bolt un-stucker", chisel, grinder, flame wrench (can't be stuck if it liquid), 5 gallon bucket of "choice words"......

    Then you put the correct combination wrench on it, and it's almost finger tight.................
     
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  8. IDIoit

    IDIoit MachinistFabricator Supporting Member

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    rust?
    never heard of her

    13083113_1350837638266674_361213310457686717_n.jpg
     
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  9. Macrobb

    Macrobb Full Access Member

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    Swapping the yoke just takes a socket and a breaker bar. Usually they end up loose more than anything, but it's not particularly hard.
    If you want to be fancy, get a 'crush sleeve delete' kit for the pinion and install it at the same time. The entire job is about ~30 bolts - pull the diff cover, pull each axle shaft out at each side(outermost bolts on each axle end), then 4 bolts to yank the carrier out. The pinion just slides right out with the yoke off.

    I've done this job in about ~2 hours by myself, including picking up and putting away tools.

    I think it'd be a lot easier than trying to swap a whole axle.
     
  10. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    See? I hate people like that.-cuss I'd LOVE to have that truck if it actually had an IDI in which it doesn't appear to.
     
  11. u2slow

    u2slow Plan B

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    I really don't like simple yoke swaps on crush sleeve diffs. Unless you've done it a few times with proven results, its easy to have it too loose and comes apart, or too tight and burn up the pinion bearings.

    The crush-sleeve eliminator can probably be swapped in without touching the carrier - I'm 95% sure I did it on a dodge 8.25" diff. You will need a pinion seal though. The outer pinion bearing can usually be coaxed out as its not press-fit. Shim the eliminator to the same size as the old crush sleeve. Re-assemble at full torque.
     
  12. BlackNoma

    BlackNoma Full Access Member

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    https://www.blueovaltrucks.com/tech...y-your-ford-truck-axle-from-the-door-sticker/

    Rear axle swap isn't hard, but the Sterling 10.25 weighs a little bit. A good rolling floor jack and/or a good friend with a strong back is necessary.
    I've done a swap on a 94 2wd cclwb 350 in about 5 hours start to finish in a driveway with nothing special.

    Check the door tag on your truck, most common is the 10.25, but there were some older trucks with Dana 70's.
     
  13. IDIoit

    IDIoit MachinistFabricator Supporting Member

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    was a 460 truck.
    and as nice as it was it was going to cost too much to get back on the road.
    registration was going to cost 3k-ish
     
  14. compressionignitionrules

    compressionignitionrules Full Access Member

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    1983 and 1984 and only F250, and if I recall correct only on 460 and 6.9 diesel. the Dana 70s were rare and all the ones I saved were powerlock equipped. a great offroading diff , very smooth centre housing slip through the mud like butta and still had 35spline axles, BUT they only came with internal drums on hubs.
     
  15. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    Didn't they also have left hand threads on the driver's side lug nuts too? I think I had one years ago and it did come out of a 1984 F250.
     

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