1978 3/4 ton to 1970 3/4 ton axle swap question

[ReeseBobby]

I'm preparing to swap out the axles in my 1970 3/4 ton leaf spring truck. It's got 4.56's and I'm looking for a little better highway travel. I've got a line on a set of 1978 3/4 ton axles in 3.73. Its a 14 bolt rear and Dana 44 front.

My question is: will these years easily swap? The front axle also has a flattop steering knuckle and fabbed crossover steering arm. He also has a factory arm available. This would be my first swap and I'm worried about wasting time and money on non-working parts. Thanks!
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[andrewmp6]

Which axles do you have in your truck now?I would rather rebuild and regear what i have vs buying something used that who knows what shape its really in.

[GMC674x4]

Originally Posted by ReeseBobby

I've got a line on a set of 1978 3/4 ton axles in 3.73. Its a 14 bolt rear and Dana 44 front.

My question is: will these years easily swap? The front axle also has a flattop steering knuckle and fabbed crossover steering arm. He also has a factory arm available. This would be my first swap and I'm worried about wasting time and money on non-working parts. Thanks!
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The front Dana 44 will swap is no problem, it will bolt right in. This is common on pre 71 GM 4x4s where guys want to do away with the older close knuckled drum brake front ends, to the more economical open knuckle front axles where parts availability is more common.



but the rear axle will not swap in directly, I'm assuming you've either got a Dana 60 or EATON HO 52 rear axle as of now, and in order to do the 14 bolt swap, you will need to cut and reposition the spring pads on the 14 bolt, as they are either closer to or farther out from the center.

[ReeseBobby]

I'm guessing I'll need new U-bolts for the rear end? Any other parts I would need to have in advance?

Thanks!

[mjensen]

In the front, I swapped in a Corporate out of a mid 80's GM diesel. No problems there. The rear had an HO52 in it, and I've swapped it for a 14 bolt FF out of a 90's square body 1 ton. It bolted right in other than the shock mounts. My '69 had both shocks facing forward, and the newer style is staggered. I would have preferred to stagger them, but my rear mount tank didn't give me that option.

As far as needed parts, definitely go for new U bolts, and you might want to verify that the U joint styles are the same. It seems like the rear is different on the newer style, but I'm not positive.