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1972 K20 Beefing Up Suspension/Frame/Axles and What Not

Discussion in 'Chevy Trucks' started by fedspunisher, Jun 27, 2008.

  1. fedspunisher

    fedspunisher Member
    from Iowa
    Messages: 89

    Have a buddy how wants me to do a 5.9L Cummins Swap into his 1972 K20. I have read the frame and suspension will need strengthened. Does anyone know what would be a good route to go on this? He plans on using it to haul with. Needs to be tough and durable. I need to get some prices figured out so he knows what he is getting himself into.

    Thannks
     
  2. wild bill

    wild bill PlowSite.com Addict
    Messages: 1,239

    hd truck

    i think it would be easer to start with a k30 ,if you want to beef up the frame and axle's ,if you just want a godzilla truck . otherwise i think unless its going to be thrashed just use the std k20 it should be ok .
     
  3. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    It certainly can be done...and has been already but if it needs to be durable too your going to want to swap out both axles, as the light duty/small bearing Dana 44 front and antique Eaton rear axle wont take the weight or torque of the 5.9 for long. A 10 1/2 14 bolt (or Dana 70) for the back and a Dana 60 along with boxing the inside of the entire frame rails would be the bare minimum to make the truck durable as well as rigid torsionally.

    Engine compartment is roomy enough for the engine. It's the radiator support that makes the plumbing and intercooling a nightmare since it's just not deep enough without major under hood surgery. Stock engine cross member will need to come out and a custom one hand fabricated and installed as well in order to get the engine low enough in the chassis, the 5.9's are tall! A minimum of a 4" suspension or 3" body lift will help greatly when dealing with the engine height/oil pan clearance as well.

    What trans would you intend to use behind it? There's plenty of engines to trans adapters for the 6BT Cummins...so choices are plentiful.

    As to the cost of a project of this magnitude, it would depend on what your labor rate is and which series engine you want to run (12V, 24V) but with purchasing an engine that needs nothing (ready to drop in "as is"), along with any trans adapter you may need, and whatever axle and frame upgrades...figure on $10-$12,000 AT THE ABSOLUTE BARE MINIMUM.

    That's if your using the existing trans. Trans upgrades would be extra of course. :)
     
  4. Sydenstricker Landscaping

    Sydenstricker Landscaping PlowSite Veteran
    Messages: 3,882

    Got a better idea.........Find a wrecked newer Chevy with the Dmax/Ally in it. Make sure the frame, etc is still good and not bent and the drivetrain is good. Take off the body and put the 72 body on top of the newer frame. I think that and a nice SFA conversion would be somewhat easier than the cummins swap. Plus it would still be all Chevy and the frame would already be way heavier than the old 72 frameussmileyflag
     
  5. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Or restore the classic 72 and buy a newer diesel truck for 10K.
     
  6. fedspunisher

    fedspunisher Member
    from Iowa
    Messages: 89

    Would the 72 k20 have a the dana 44 and the eaton rear? What year was the 1st year they made k30? If i could find one of those i would just put a 72 cab on it and call it a day.
     
  7. Sydenstricker Landscaping

    Sydenstricker Landscaping PlowSite Veteran
    Messages: 3,882

    Yes the 72 would have the D44 and the Eaton rear. It wasnt until 73 that they started making the good 14 bolt rear ends. They stopped using the D44 front in change for the Corporate 10 bolts in 1980 I beleive. Not sure on the first year of the K30's. But if they made them in 72', good luck finding one that is in any kind of decent shape or finding one for that matter.
     
  8. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    '77 was the first model year for the K30's in any cab configuration from the factory. Whether it was a regular, crew, or bonus cab.

    Previously however you could purchase a new C30 and and aftermarket supplier (Quigly mainly in the 70's) would install the 4X4 components and maintain the factory warranty.
     
    Last edited: Jul 10, 2008