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post #1 of (permalink) Old 05-17-2002, 09:15 PM Thread Starter
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Difference in D44 front between 72 and 73?

Just wondering if there is any diffrence in the front axles between 72 and 73, want to kow if my late model(73) axleshafts will work i a 72 im gonna get.
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post #2 of (permalink) Old 05-17-2002, 11:45 PM
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Re: Difference in D44 front between 72 and 73?

If there is a difference, I don't know what it would be. I would say that they are the same.
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post #3 of (permalink) Old 05-18-2002, 06:35 AM
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Re: Difference in D44 front between 72 and 73?

72 was the first year of the open knuckle, the 73 will be the same one.
The axle shafts from my 78 D44 2nd design are the same as the 76 external hub 1st design one that I now have under it.
With 72 being the 1st year for open knuckles the one you are lookin at isn't by chance a closed knuckle one is it?
Tweener years have a problem with them tossing in what ever they had left over at the factory.
Although I have never seen a closed knuckle being on a 72, But I have only seen a few of the how many that were produced?
Just like 77 being the year they went to the 2nd design I have seen many with the 1st one spindles.
But being that the open ones are the better I doubt that GM would put them on in 72 they most likely just scrapped the old axles.

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post #4 of (permalink) Old 05-18-2002, 11:56 AM Thread Starter
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Re: Difference in D44 front between 72 and 73?

Tell ya the truth, i dont know if there open or closed knuckle, i never even thought about it, it is disk brakes though. Are the spring perches in the same spot? well i guess i could break out the measureing tape.
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post #5 of (permalink) Old 05-18-2002, 05:38 PM
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Re: Difference in D44 front between 72 and 73?

Well there ya go, disk brakes. Open knuckle.
yes the spring perches will be in the same location.
Here is a bit of info that ya might find interesting.
GM has two different types of axles: the "first design" and the "second design". For those who dont know the difference, the "first" goes from 72-76. The "second" goes from 77 to 91. Some differences are:

1. Backing plates are ALL diffferent. Both 1/2 and 3/4 ton for both designs are NOT the same thing. 3/4 tons are larger diameter than the 1/2 tons. There are currently 6 different types of backing plates. The 1/2 ton has the 72-76, 77-80, and 81-91. 3/4 ton is the same years, but only bigger around.

2. Bearing hub and rotors are different. There are 4 types. 73-76 use a smaller wheel bearing on both the 1/2 and 3/4 ton. The 1/2 ton bearing hub is an internal drive. 3/4 tons were available in both the internal and external drives. 77 and newer bearing hubs are the same size wheel bearing. 1/2 and 3/4 tons are all internal drives. The differences in the rotor diameter is the fact that the 3/4 tons are larger around than the 1/2 tons. This is why the backing plates are larger around than the 1/2 tons. If you use a 1/2 ton backing plate on a 3/4 ton rotor, the caliper will NOT even align up with the bolts. If the 1/2 ton rotor is used with the 3/4 ton backing plates, the caliper will NOT have enough pad contact with the rotor.

3. Spindles. 73-76 are one type only. They are "first design" small bearings. 1/2 and 3/4 ton spindles are interchangable. 77-91 spindles are "second design" and all interchangable between 1/2 and 3/4 tons. You cannot use a first design spindle with a second design bearing hub & rotor. The hub will wobble in place. If the second design spindle is used with a first design bearing hub, the hub will not even go on at all.

4. D44 and 10B axle shafts are not interchangable. The D44 shafts measure: right - 36.13"
left - 18.31"
10B shafts measure: right - 35.46"
left - 19.15"

5. Steering knuckles. D44's have the infamous "flat top" knuckles on the passenger side. These are good for the crossover steering for where the steering arm is mounted on top of the knuckle after machine work and drilling has been done. The 10B knuckles have NO flat surface whatsoever. Machine work would be excessive to make the crossover work and therefore would be easier and cheaper to locate the correct knuckle off a D44.

All in all, when doing a swap like this, try to round up the parts off one truck to use on the other. Such parts to swap over would be: backing plates, spindles, bearing hub & rotors, and if desired for crossover steering, the knuckles.

The knuckles do NOT need to be changed if you do not plan on the crossover steering.

It all boils down to this: D44 and 10B parts ARE interchangable from the knuckles out. Anything else from the knuckles in is NOT interchangable.

ALL calipers on both D44 and 10B are compatible with either axle. Even the first and second design axles are compatible with BOTH 1/2 and 3/4 ton calipers. So, whatever swap you plan on doing, you can retain your stock calipers.
When stepping up to the big D60, this is a whole different ball game. Nothing is interchangable from the D44 and 10B to the D60

Info provided by ThatK30guy to me a few months back.

post #6 of (permalink) Old 05-19-2002, 08:15 PM
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Re: Difference in D44 front between 72 and 73?

are you sure 1972 was the first year for closed knuckles? I thought it was 1971... which was also the first year for disc brakes.
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