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Help me identify my Dana 70 HD!

Discussion in 'The Garage' started by JeffHK5, Apr 2, 2005.

  1. JeffHK5

    JeffHK5 1/2 ton status

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    I got a good deal on a Dana 70 at a parts yard but I'm not sure what it is.
    With the diff on jack stands and the pinion pointed up it has 70-3HD on one
    web,70-3HD/176A on one web and 42260/2 on one web and what looks to be
    the Dana logo in the last web.Where I put backslashes read this as a second line. The ring gear has a date of 7/4/88 on it and axles have 35 spl. and are around 1.500 in dia. It's got a 73" wms to wms. I could not find anything stamped on the tubes. Sorry for the same old question but the Dana 70
    is new to me.
    Thanks Jeff
     
  2. BlueBlazer

    BlueBlazer 1/2 ton status

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    Sounds to me like a 70HD from a GM fleetside dually.
     
  3. mofugly13

    mofugly13 1 ton bucket of rust Premium Member

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    Look at the diff cover bolts, see if there is a metal tag bolted under any of them, sometimes there's so much grime that it looks like there is no tag at all. If you fid a tag, go to www2.dana.com, click on light axle, and then identify part number. That oughta tel you what it is. Sounds like a D70 HD for sure though. Pull an axle and count the splines, if there are 35, then it's most likely a 70HD or 70U. I have heard that the HD has 4" axle tubes that are the same diameter all the way out to the backing plate mounting flange. I have a 70U and the axle tubes are 3.5" and they neck down at the last 1" or so before the backing plate mounting flange. If it's a 35 spline D70, then it's a desireable axle, whether it's an HD or a U. Pull the diff cover and look inside also, you may have been lucky enough to have scored one with a Powerlok.

    Geez, I read your post the first time around and totally missed that you already counted the splines. Sounds like a 70HD to me.
     
  4. Eric M.

    Eric M. 1/2 ton status

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    I agree. The rearend is out of a dually pickup. Are you building a dually or planning on running Hummer rims? That sucker is wide.

    Eric M.
     
  5. JeffHK5

    JeffHK5 1/2 ton status

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    Yep, Hummer wheels. All the #'s make me think that this a 70HD but when I mic'd the tubes there 3.5". I was told buy local GM parts house that this is a HD type 70 ,if it where a U type diff it would have the U marking on it somewhere and not 70-3HD on the webs.They also told me that it's a mith
    about Dana 70 HD's all having 4." tubes. Don't know if this guy knows squat
    about diffs but he was looking at a computer screen and reading stuff outloud to me.
    Thanks Jeff
     
  6. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    Seems like I remember there being something odd about 70-3HD's but I'm not sure. What's the gear ratio? Do you know what type of truck that axle came out of?

    As far as I know all of the D70HD's that GM used had 4" tubes.
     
  7. atho

    atho 1/2 ton status

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    can you find a BOM # stamped into one of the axletubes?

    take it to the translator at www.drivetrainsuperstores.com

    and let us know whatcha got
     
  8. JeffHK5

    JeffHK5 1/2 ton status

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    This rear has a 4.10 gear with a open one peice diff. It had dual wheels on it
    when I got it and at a width of 73" it would have to be a dually. Inside of each spring perch is a larger pad that looks like whatever it came off had
    one hell of a set of overload springs.This housing has 70-3HD all over it and not U once. I have heard that the only difference between the HD and the U
    is tube wall thickness and O.D of some bearings?
    Thanks Jeff
     
  9. Eric M.

    Eric M. 1/2 ton status

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    Good point. I'll have to measure my D70 HD housings, but I'm almost positive they are 4". I know they are considerably larger than the 14 Bolt FF which are 3 3/8". Wonder what the deal is with the "3" there?

    Eric M.
     
  10. JeffHK5

    JeffHK5 1/2 ton status

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    Well I found my BOM# 605397, its a 88-91 only, dually heavy duty Dana
    70-3HD. I saw some various posts on it on pirate and even though it's
    very heavy duty most people stay away from it because of the lack of info
    about what parts it shares with other Dana 70's. If I can get a Detroit locker
    ,4.56 gears and a rebuild kit for it i'm gonna give it a shot. Maybe i'm breaking
    some new ground or something. Or maybe i'm throwing a grand in the crapper!
    Thanks Jeff
     
  11. u2slow

    u2slow 1/2 ton status

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    This extra pad tells me its from a 88-98 style truck. I believe its just for the rubber bumpstop.

    You will have to find out if you have 5/8" or 21/32" pinion offset before you buy gears & locker.
     
  12. James670X

    James670X 1/2 ton status

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    I have the Dana 70HD under my 1988 Chevrolet V30, if you need pictures or measurements from it just ask.
     
  13. JeffHK5

    JeffHK5 1/2 ton status

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    Dana 70-3HD

    Thanks but I think I got it now. The "3" in 70-3HD is the note for the 21/32 pinion offset, which is not what you want. It does not allow for a lower gear than 4.10 , atleast not a Dana gear. I can get what a few shops are calling a custom gear , by custom they mean DAM HIGH PRICED ! Try 429.00 for just R&P! I'm now looking for a Dana 70HD 73" wms/wms with 4" tubes. Lucky for me I only paid 150.00 for the 70-3HD.

    Thanks Jeff
     
  14. tjwrang

    tjwrang Newbie

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    I have a d70-3hd and I didnt know it either until after I built he truss and everything else. I set the gears up and found how hard it is to mesh. Now I have a loud coast noise which I am trying to find the remedy to it right now. some have said go with a ring spacer but I am having a hard time accepting that.

    Atho I am sure I am correct by the Dana Expert site but here is mine. 605345-5 Mine shows to be a 3.73 but it had a 4.10 in it.

    How do we measure to be sure of what we are dealing with?

    Thank you,
     
  15. merace19

    merace19 1/2 ton status

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    Why all this trouble to use a Dana 70 when the 14 bolts are every where?
     
  16. tjwrang

    tjwrang Newbie

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    I just wanted to only look for dana parts. stupid reason but its what i wanted. I also liked the smaller narower housing but just as strong.
     
  17. boz42

    boz42 1/2 ton status GMOTM Winner

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    As noted earlier in this thread, it is to run H-1 rims.
     
  18. Speedo

    Speedo 1/2 ton status Premium Member

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    If you have the old r&p you can use the part numbers from them to identify what pinion offset you have.

    Gus
     
  19. merace19

    merace19 1/2 ton status

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    Not to hijack but 14bolt wont work?:confused:
     
  20. boz42

    boz42 1/2 ton status GMOTM Winner

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    Not w/out wheel spacers. The 70HD does not need spacers.
     

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