Eaton HO72 rear axle

[Andy4639]

Dumb question but I have to ask.

How do I know what year the rear end is? I have no idea. This truck is pieced together from different years. Is there a mark on the rear end some where are does the numbers I posted give me my answer. It looks like they are all the same for our models. Mine having the load bolt helps. What parts manual do I need to look for?
Thanks for all the info so far.

[DeadheadNM]

Look here for axle ID information: http://67-72chevytrucks.com/vboard/s...d.php?t=590959

The parts are out there. It just takes some sleuthing but that keeps things fun - like hunting. Here’s the manual I’ve made use of:

[Andy4639]

$200.00 for a manual! I guess I need to do some searching.

[DeadheadNM]

Originally Posted by Andy4639

$200.00 for a manual! I guess I need to do some searching.

How about a free electronic version then? Buy Ron a beer sometime

Link: http://67-72chevytrucks.com/vboard/s...d.php?t=817560

[RPOZ11]

Andy4639 :

PM sent

[Andy4639]

Thanks, I got it. Hope your doing better sir.

[davischevy]

Subscribed.

[conoco]

Originally Posted by RPOZ11

They are geared low.
I believe mine is a 4:11.
Originality.
Decided to run the HO.
(I have an extra HO drum to drum)
Gear Vendor will assist in my highway mileage ; but probably not enough.
I think there was a 3:90 gear GM offered; or something like that.
Can't recall the 3 series ratio.
Very hard to locate those.

I have a 14 Bolt that I considered using.
3:42 posi in that one.
Just need to move and install spring pads correctly onto it in order to use that one.

I have the Eaton with 4.11 in my truck. Also 4inch lift and 35s . I also have the Gear vendors add on. Before the gear vendors I would be at 3500 rpm at 70mph. After the gear vendors install I am now at 2-2400 at 70mph. It was by far worth every penny. I understand why people would prefer the 14 bolt to the Eaton, but I love my Eaton. If I wasn't able to add the gear vendor kit I probably would have swapped. It was to loud at 3500 rpm when driving it for fishing trips. Also I drive my truck all across Alaska and the gear vendor kit has be amazing through all the elevations.

[DeadheadNM]

Adding this to document location of the locker tag (borrowed from Mike Cofield).

[cangim]

I have a c30 dually that I am keeping the HO72 axle as I like the way it looks, my question is for general driving, is the locker obnoxious and better to just keep an open diff? I am planning to move to 30 spline spiders/axle shaft. The cost between spiders vs locker isn’t that much.

[bry593]

Originally Posted by cangim

is the locker obnoxious and better to just keep an open diff?

The locker is awesome if you use your truck as a truck. Pretty much eliminates getting stuck. However, there are a few things that might bother some people:

1. When letting off throttle and reapplying, one wheel will be powered until the backlash is removed. This tends to make your truck dart to one side of the road. Not a scary amount, but something to be aware of.
2. When letting off the throttle, the locker will uncouple and send a "pop" vibration up the driveshaft. If you don't know what it is, you might think something is wrong in the drivetrain.
3. Quick acceleration around corners will almost always cause a chirp of one tire as there is no differential (one wheel has to turn faster than the other in a corner).
4. Because of #3, driving on snow or ice with highway tires could send you into a spin-out.

All four are not enough for me to ever want to go back to an open diff. So much better with a locker. I hate getting stuck on a tiny mud puddle or wet grass.

[bry593]

Originally Posted by BigBird05

Does it matter what size brakes you have? Are all E-bakes parts for HO52 and HO72 the same?

I can tell you that most of the components of a 14-bolt brake hardware kit fit the HO52/72. However, the spring cups have a different pivot diameter and are not compatible. This also means that you can't use a 14-bolt self adjustment arm. This is also a reason you can't use 14-bolt brake shoes.

The star adjustment screw assemblies are compatible, as are the springs (one return spring has an extra bend but still works). You will also need the strut rod springs from a 14-bolt thru late model axle as these are not in the hardware kit. That strut spring stayed the same all the way up through the 2000's. Buy strut springs for a 2000 Chevy Express 3/4 ton and these will work fine.

[cangim]

Originally Posted by bry593

The locker is awesome if you use your truck as a truck. Pretty much eliminates getting stuck. However, there are a few things that might bother some people:

1. When letting off throttle and reapplying, one wheel will be powered until the backlash is removed. This tends to make your truck dart to one side of the road. Not a scary amount, but something to be aware of.
2. When letting off the throttle, the locker will uncouple and send a "pop" vibration up the driveshaft. If you don't know what it is, you might think something is wrong in the drivetrain.
3. Quick acceleration around corners will almost always cause a chirp of one tire as there is no differential (one wheel has to turn faster than the other in a corner).
4. Because of #3, driving on snow or ice with highway tires could send you into a spin-out.

All four are not enough for me to ever want to go back to an open diff. So much better with a locker. I hate getting stuck on a tiny mud puddle or wet grass.

This is excellent! Thank you for the insight