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What rear End do I have

Discussion in 'Chevy Trucks' started by willysbill, Mar 27, 2003.

  1. willysbill

    willysbill Junior Member
    Messages: 13

    I have just purchased a Duallie Chevy Rear End, unfortunately It doesn't have an ID tag on it.
    What sort of Truck did it come from.
    What year
    What Ratio could it be.
    Are there any web sites which could give me any information.
    There are photo's of the rear end posted on the web site below.

  2. Chuck Smith

    Chuck Smith 2000 Club Member
    from NJ
    Messages: 2,317

    It is a GM corporate 14 bolt axle. Full floater, 10.5" ring gear. Used from 73 - 87 for sure, and maybe later too. Gear ratios went from 4.09 - 5.11 (most common).

  3. willysbill

    willysbill Junior Member
    Messages: 13

    Hi Chuck
    Thank you very much for that info, it's always good to know what sort of a rear you have.

  4. tileman

    tileman Member
    Messages: 55

    rear end

    chuck, dont want to doubt you but i believe it is either a dana 60 or dana 70 rear. those are the only full floaters that gm used. the corporate 14 is a semi floater. i got my info from the jan 03 issue of four wheeler mag. they said that heavy duty 70 where under the rear of 73-91 chevy dualie . and ratios are 3.54-7.71. the easy way to find the ratio is to open the case spin the ring till a series of numbers come then you will find something like 9-48 or the like. this is your pinion to ring number divide the into the little to get the gear set hope it helps no hard feelings chuck.
  5. Chuck Smith

    Chuck Smith 2000 Club Member
    from NJ
    Messages: 2,317

    Well, you (they) are wrong. The semi floater is in fact a 14 bolt, but it has a 9.5" ring gear, and is referred to as the "small" 14 bolt. The larger 14 bolt full floater has a 10.5" ring gear. GM did not use Dana 60 rear axles from 62 - 87. GM also used the 14 bolt Full floater in some duallies as well. Remember this.... ONLY the GM 14 bolt has 14 bolts holding the cover on. The Dana 44, Dana 60, and Dana 70, all have 10 bolts holding the cover on. :)

    Rather than try to explain and back up my fact, check out this web page....


    Or this one


    (This guide is originally from Four Wheeler Magazine)

    No hard feelings :)

  6. tileman

    tileman Member
    Messages: 55

    rear end

    thanks chuck, i stand corrected. my info was not complete. thank you for the cool links. i have been confused about that for awhile. since you seem to know alot. do you know how to get the second link to print? thanks again for the help.
  7. willysbill

    willysbill Junior Member
    Messages: 13

    Ok Chuck & tileman
    Now I am confused:confused:
    My Rear end has 14 Bolts holding the Cover on.
    The numbers on the ring gear GM 3993444 8 41 1 73
    So that makes mine a 5.1 ? Ratio.
    So if I understand correctly Mine is GM 14 Bolt Duallie.
    Is that correct.
    Isn't the internet a wonderfull thing.
    Thanks for all the advice guys

    Bill in Oz
  8. Chuck Smith

    Chuck Smith 2000 Club Member
    from NJ
    Messages: 2,317

    Tileman, I have no idea why the ColoradoK5 page won't print? There has to be a way to get it to print. I will check it out again.


    "The numbers on the ring gear GM 3993444 8 41 1 73
    So that makes mine a 5.1 ? Ratio."

    Where do you get the 5.1 from? You lost me :confused:

    Yes, you gave a GM 14 Bolt duallie axle. I tried to look at it again, but you "exceeded your 20 meg limit" :(

    You should be able to call a GM dealer, and give them the part number off the ring gear (which you have 3993444 8 41 1 73) and they should be able to tell you what the ratio is. You could also count the teeth on the ring gear, and the pinion gear, and divide (# of pinion gear teeth into # of ring gear teeth) to get the ratio. 4.56 is common, and 5.10 is less common, but possible.

    From the "41 1" in the part number, it might be that your ratio is 4.10:1. That's just a guess though.

  9. willysbill

    willysbill Junior Member
    Messages: 13

    Hi Chuck
    I thought that was the way you were supposed to do it
    8 into 41 guess I am wrong again.
    20meg limit happens every now and then, I must be too popular.
    I suppose if I emailed GM they might tell what the ratio is.
    Thanks for all your assistance.


    View attachment c30 diff 006.jpg
  10. DrMaserati

    DrMaserati Junior Member
    Messages: 11

    Being the new guy around here I feel a little uncomfortable saying this, but I would have to respectfully disagree with you. My 78 K30 duallie came from the factory with a Dana rear, and the factory service manual covers three axles that were available that year. The Dana 60 and 70, which they refer to as the Dana 9-3/4" and Dana 10-1/2", and the corporate 14 bolt, which they refer to as the Chevrolet 10-1/2".

    What baffles me is how they decided which they were going to use, Dana or corporate. Seems like they just flipped a coin. Or perhaps it was determined by where the truck was assembled.

  11. Chuck Smith

    Chuck Smith 2000 Club Member
    from NJ
    Messages: 2,317

    JP, welcome aboard :waving:

    Feel free to correct anyone here, as long as you have facts (you can always butt in with your opinion too). GM flipped a coin on a lot of things it seems. I recall my 77 manual mentions all the GM axles, and says to consult the HD Truck manual for the 12.5" ring gear GM axle. It does mention Dana axles up front, but not in the rear. From 62 - 72 GM liked to use an Eaton rear axle too (in addition to the 12 bolt). It just seems the 14 bolt is the most commonly used rear axle in 3/4 and 1 ton trucks from 73 - 87, and even today in some models (in another thread they mention it seems to be with the 454 motor).

    There is a great thread here on front axles, I'll see if I can dig it up. Seems there was 3 or 4 different ones used, again, by flipping a coin.

  12. Chuck Smith

    Chuck Smith 2000 Club Member
    from NJ
    Messages: 2,317

  13. Joey D

    Joey D Senior Member
    Messages: 280

    I can't say for sure the years, but the dana 70 was installed in some dually trucks. Maybe due to part restraints.
  14. plowking35

    plowking35 2000 Club Member
    from SE CT
    Messages: 2,923

    Ok here is the dealio.
    " Beyond the odd Eaton or Rockwell axel in the medium or heavy duty line, GM has used either their own corp. sourced axels, or units from dana spicer. In the olden days, GM 's axels were built at one of their facotries or contracted out to companies like Detroit Gear and Axel. After WW2, GM formed the Saginaw Div., which included an axel subsidiary. From that point, most of GM car and light truck axels were built in house, many at the Buffalo New York Plant. These are commonly know as Saginaw or Corporate axels. In 1994 the axel division was spun off into a new corporate identity, American Axel and Manufacturing. The axel didnt change, just the corportate identity. GM is still thier largest customer, but they have recently begun building axels for other OEM's." as quoted from the December/ January issue of Off road Adventures
    However when production at AAC ran behind, dana was used to suppliment the assembly line. That is why some GM 1/2 and 3/4 ton trucks post 76 have dana front ends, due to the limited number of 1 ton front ends needed, AAC never designed a unit for that and all DANA axels were used.
    The 86 chevy that I am completing got its axels from an 80 dually pick up, and it has a dana 70 rear, and 60 front, however all my other gm one tons that I have owned have had a AAC rear.
    Here is a rundown of dana axels and their applications for GM
    Dana 45 Rear 56-62 1/2 tons
    Dana 60 rear 57-92 3/4 tons in latter years used mostly in G series vans
    Dana 44 front 60-81 1/2-3/4 tons by 78 most trucks had the corp 10 bolt, but GM used them in limited numbers through 81
    Dana 44 rear 63-68 1/2 ton very rare used only when 12 bolt corps were in short supply
    Dana 60 front 77-92 1 ton also used in the M 1008 CUCV militarized Chevy p/u
    Dana 70 rear 73-94 1 ton and up used mostly in commercial applications such as motorhomes and step vans till 79 when it started showing up in dually p/u. It is not very common, and used when corp 14 bolts were not available. Used till 92 and then disappears from dana's books for those applications. 2 versions exist of this unit, one called the 70 HD and the 70U, u stands for undersized bearings, and is the weaker of the two. But the HD seems much more common.
    Dana 80 Rear 92-up 1 Ton pick up mostly in p series vans
    Last edited: Apr 6, 2003
  15. willysbill

    willysbill Junior Member
    Messages: 13

    Hi Guys
    Ok I the one that started this thread and I am still confused, watching and reading all the posts, I find I am still not enlightened as to what I have, the discussion seems to have gone from the rear end to the front end.
    I have attached another pic (I hope) to try and clarify the rear end identification problem.
    Please help.

    c30 diff 006.jpg
  16. Chuck Smith

    Chuck Smith 2000 Club Member
    from NJ
    Messages: 2,317

    Sorry I wasn't more clear. You have the GM 14 Bolt, 10.5" ring gear, full floating axle. It is called a "14 bolt" because there are 14 bolts holding the rear cover on (which you can plainly see in the picture).

    The Dana 44, Dana 60, and Dana 70, ALL have 10 bolts holding the rear cover on. Obviously there are other differences that distinguish all of these axles, but rest assured, you have a GM 14 bolt as I said above.

    Don't mind the discussion jumping around, once we get on a topic (such as axles) everyone wants to post all the facts they can on the topic, which I think is a great resource for all of us. Front axles, rear axles, etc. This thread will turn up in a search someday, and really help someone like yourself. :)

  17. Chuck Smith

    Chuck Smith 2000 Club Member
    from NJ
    Messages: 2,317

    Here is a pic of the GM 14 bolt in my 77 Chevy K/20. Look familiar?


  18. JohnnyU

    JohnnyU 2000 Club Member
    Messages: 2,040


    I thought they were called 10/12/14 bolts because there were 10/12/14 bolts that held the ring gear to the carrier?
  19. willysbill

    willysbill Junior Member
    Messages: 13

    Hi Chuck
    Thanks for that, I didn't want to be a pain in the rear, but I had to have it clarified.
    One other little question which has been bugging me, I see a lot of mention about K10 K20 K30 but hardly any on C30 are they an oddball thing or only exported to countries like Australia, everybody over here refers to Chevy Trucks/Pickups with the C prefix and not the K, just wondering

  20. Chuck Smith

    Chuck Smith 2000 Club Member
    from NJ
    Messages: 2,317

    C= 2wd
    K= 4wd

    For Chevy, it's 10 (1/2 ton), 20 (3/4 ton), and 30 (1 ton).

    For GMC, it's 15, 25 and 35. Same trucks, only minor differences.

    Snowybowtie, never heard of the number of bolts holding the ring gear on as far as 10 bolt, 12 bolt etc. :confused: