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Who knows what gears fit in stock cases?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bigwheels6, Jan 30, 2001.

  1. bigwheels6

    bigwheels6 Registered Member

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    I have stock 74 axles in my Jimmy (GM 12 bolt in rear and Dana 44 in front I think) and I want to gear up. I have 3.73 right now, and I'm thinking about a beefed up 700 R4 and 38" tires, so the gears have to go. I'd like to see something in the 5.xx range, but I don't know what fits in my cases. Anyone have any experience here?

    In every contest there must be a loser.
     
  2. HarryH3

    HarryH3 1 ton status Author

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    5 series gears are going to have some very tiny teeth in axles that small. I'd seriously suggest looking for a 14-bolt FF/Dana 60 combo. You'll be money ahead in the long run. You might even get away with a Dana 44 or a 10-bolt up front, since the rear seems to take most of the abuse. It depends on your driving style.

    I couldn't keep teeth on the ring gears of 12-bolts with just 4.10's. Spit the teeth out 3 times in 3 years and this was with just 36's. (Q78-15's). 5 series gears are even weaker. That truck did have an SM465 tranny, so the shock loading was a bit higher than you'll see with a slush-box, but just the same, the bigger axles will take tons more abuse. I suggest that you take the money you were going to spend on new gears and start looking for beefier axles. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     
  3. KENBARBOUR

    KENBARBOUR Registered Member

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    After breaking 5 12 bolts in two years (used ones) I finally built up one with all new parts for my 35" bfg's. I used 4.56 Richmond gears. Quess how long it lasted? 1 week
    Now I'm bolting in a 14 bolt ff after wasting all this money.
     
  4. flcpl4fn

    flcpl4fn 1/2 ton status

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    I have 4.88's in my 10 bolts with 38's, and haven't had any problem with them.

    '85 Jimmy in Jax, Fl
     
  5. BurbinOR

    BurbinOR 3/4 ton status

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    Depending on your driving style, those 10/12 bolts won't last long.............especially if you truly are running dunes out at Florence or Sand Lake under power. Yep, another Oregonian here, where are you located? Gresham here, Mudhog about 15 minutes from me, lots of other NW guys here.

    Rearend especially would go for a 14 bolt, even if it is a SF 6 lug pattern.

    <font color=orange>'79 - 406 TPI -<font color=orange> K5#5 - <font color=blue>See it at---&gt;<A target="_blank" HREF=http://www.blazzinor.coloradok5.com>http://www.blazzinor.coloradok5.com</A>
     

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