Differences between 1978 D44 and 1984 10 Bolt front axles

[mbood82]

I recently swapped axles on my '84 half ton. I got donor axles from a '78 3/4 ton chevy, a D44 and 14bff. All the research I got said it should all be bolt in, which is mostly was. However, I found the front axle tubes appear to be a 1/4" narrower then the original one. In addition, I have been chasing some wobble for the past few months. I know that the tires are likely to be one of the contributing causes but from my Jeep experience I know the caster is often an issue. What are the chances that the caster is changed between the '78 and '84 front axles? Meaning, with the axle spring perches bolted flat onto the same springs the old one was, will the effective caster angle be different?

This is the truck in question:

 

[4X4HIGH]

There were two different diameter axles tubes on the D44 axles, not sure on the 10 bolt axles but fairly sure they were all the same. I doubt that caster angle changed at all between the two different diffs.

 

[Hogback Fabrication]

Both axles should have 3" tubes and should have the same WMS (wheel mounting surface, i.e. they should be the same width).

Your "wobble" is likely caused by worn out steering components, balljoints, wheel bearings or alignment.

 

[mbood82]

This one definitally has a narrower axle tube then the stock one.

WMS seems similar, not too concerned about that.

The balljoints are new, the tie rod ends from pitman arm to steering knuckle are brand new, the tie-rod ends on the tie-rod bar are in good shape, the bearings are tight. I've been through all those items, the only items left are the steering box or rag joint. Alignment (toe) is just barely in. Caster is the only item left and seems to be a big contributing factor on wobble usually, hence my asking.

 

[Hogback Fabrication]

This one definitally has a narrower axle tube then the stock one.

WMS seems similar, not too concerned about that.

The balljoints are new, the tie rod ends from pitman arm to steering knuckle are brand new, the tie-rod ends on the tie-rod bar are in good shape, the bearings are tight. I've been through all those items, the only items left are the steering box or rag joint. Alignment (toe) is just barely in. Caster is the only item left and seems to be a big contributing factor on wobble usually, hence my asking.

'77 and down axles should have had 2 7/8" tubes, maybe yours is one from the end of that run.

Get an angle finder and measure the caster but I'm pretty sure they never made a change. Have someone else move the steering wheel back and forth while you are under the truck and make sure everything in the steering is tight.

Sometimes unbalanced tires can cause that wobble.

 

[mbood82]

'77 and down axles should have had 2 7/8" tubes, maybe yours is one from the end of that run.

Get an angle finder and measure the caster but I'm pretty sure they never made a change. Have someone else move the steering wheel back and forth while you are under the truck and make sure everything in the steering is tight.

Sometimes unbalanced tires can cause that wobble.

I got the axles already separated from the truck so I wouldn't be suprised if it was actually a '77 and not a '78 as I was told.

I've both had other people look at the steering while I turn the wheel and watched it myself, all the components are tight. The tires are only balanced with that equal stuff though so at this point I'm fairly convinced it is the tires, I just wanted to make sure there weren't any other possible causes and the tires were just amplifying it.