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can i swap a 1972 2wd 3/4 rear end into my 81k20?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Rix_Gotta_Blazer, Jun 8, 2003.

  1. Rix_Gotta_Blazer

    Rix_Gotta_Blazer 1/2 ton status

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    i ve got a 72 3/4 ton 2wheel drive parts truck. i was wondering if i could swap out the rear end out of it and put it into my 81 k20? as long as the gears match, will this work? will i have any problems with spring perches or drivelines? thanks in advance.
     
  2. R72K5

    R72K5 Banned

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    67-72 2wd except longhorns and C30's are all 42.5" spring centers, longhorns are 1 ton chassis built- even the C20's

    4x4 in 67-72 years were 40" centers until 73 when everything under 1 ton was changed to 42.5"

    should swap over fine, same tube diameters and perch distances and U joints should be same series

    only one minor catch: 73 moved shocks to both sides of axle housing unlike 72 and older that have shocks both on same side of housing- but thats nothing big

    get out tape measure and measure width of U joints and size of caps to be sure, and also distance form center line of axle tubes up to the pinion yoke on the 14 bolt and on the 72 eaton axle to make are are close to same- im sure are close though, and also make sure there isnt a bunch of slop betweent he ring and pinion gears int he old eaton, i have found that those old axles liked to have alot of teeth wear and pinion slop for some odd reason
    happy swapping if is same ratio!
     
  3. u2slow

    u2slow 1/2 ton status

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    I hope the 72 parts truck you have is leaf-sprung. The coil-sprung axle will require new perches for sure.

    Does it have the Eaton or the Dana? The Dana is still easy to get parts for and has more available ratios.
     
  4. R72K5

    R72K5 Banned

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    most all dana 60 were leaf and most all eaton rears were coil, tht goes for 67-72 3/4 tons, as all 1 tons were leaf sprung and only 70 or 70 and one other year could get a dana 60 semifloat for the 1/2 ton 402 trucks

    dana 60 only had three avaialble ratios 67-72, eatons could have two, 4.56 was std dana 60 ratio and 3.54 was BB ratio and 4.10 was available

    eatons were 4.57 standard and 4.10 optional



    good luck
     
  5. Rix_Gotta_Blazer

    Rix_Gotta_Blazer 1/2 ton status

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    thanks for all the replies fellas. as usual, things arent going my way, the truck is coil sprung. things just cant go nice and easy for me. the k20 is going up for sale. too many problems with DMV, rear end, and smogging.thanks again.
     

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