Eaton rearends

[JJ]

I have a 3/4 ton GMC with the "corporate/eaton rear differential, now for the question. Are these a good quality product? If you think they are, or if think they're not, please give me more than just "they're a piece of crap", please tell me why you do, or do not like them, and what's good or bad. Thanks.

[Big69C20 Toy]

Well you'll get some mixed thoughts on this one i'm sure. I like them because they can handle tons of power supposedly. I dislike them because mine has been a pain to get to seal up. The pinion, diff cover and pumpkin all have really small leaks but it gets annoying and makes the underside of the bed ugly.

I say they're good cuz they're full floater and can handle some massive power. The only bad part is getting gears or parts for these is pretty tough to find. The highest (numerically lowest) gears i can find for these are 3.90s which make them not the most economical but good powerhouses.

I'm talking about an HO72 axle myself, not the HO52 ones, cuz i've no idea on the smaller one. good luck

[Patrick Sullivan]

From what I've read, they're bulletproof, if you keep 'em properly oiled. My H072 hasn't failed me yet..

[Big69C20 Toy]

I read something on here or some other sight about a Fiberglass Hemi that kept eating up all the rearends that could be thrown at it. like 6 or so a season. they put an ho72 in and it's held for 5 years. Could all be some bs but i just rememberd so i thought i'd mention it

[Longhorn Man]

I never had a problem with the one in the old Longhorn...but I didn't get to enjoy that truck very long.

[Blue_71]

no problem out of the one in my 4x4, but ive not moved it very much yet, and not put any torque to it

[COBALT]

Back when these truck were new it was probably the best differential available for 3/4 ton suspension. Now, you'd be better off converting to a 12 bolt dana or something due to part availability and $$$.

I have two of these bad boys. The one under my daily driver suffered a severe case of the "growles" last October. Made sense since it sat in a field for over a year before I got the truck. My choices were either to quit driving it and find a new axle that wasn't the same (convert to a different axle) or get this one fixed. I got it fixed and it cost me major $$$.

I got my parts truck in November, and guess what? Same axle. This one was never serviced, but didn't make any noise. Who knows what's in that thing.

The bottom line is this:

1. Spiders aren't made for these any more. You have to get them used. That sucks, but oh well. Who really wants the 1-wheel wonder? Eaton posi units for the carrier were an option back then, but you can't get them now. Lockers are the only alternative (which I went for).

2. The carrier and pinion bearings are MONSTEROUS, and expensive as hell.

3. Gear sets are easily gotten in 3.90 (again, which I went to from 4.10). There are used 3.73s out there, but they literally vaporize on sight. Everyone wants them.

4. Labor to fix these things are bad too.

If you have one and want to keep it take care of it. I found that using the Silicone II window/door sealant (black) from the local Home Depot works great to seal these up nicely. If you have a gasket throw it away. It won't seal crap.

Since having mine fixed it's been absolutely flawless. No problems period, which means it will now last for another 35 years+.

Now, for my parts truck, well that's another story.

[crew70]

I herd you couldnt buy lockers for these thinks?
mine has a locker in it , I was told that was stock. was it a bunch of sh!t ?

[Rod]

I like them.... I have the detroit lockers in all my eatons pumpkins. I would surelike to have a set of 373 gears ... never even seen a setup. All I ever seem to see are 4.10 or 4.57 in these trucks. Saw 5:14 once I think too. You cant really find new replacement parts but the old used stuff is still out there. Simple set up to swap gear ratio's is just to replace the whole gear assembly. I have only see one set of worn out gears in the trucks I have looked at.

[Big69C20 Toy]

I called a few places, i think Randy's Ring and Pinion had new 3.90s but it was like 260 for the parts alone. I also heard these are easy to work on but i'm yet to try it.

[Vince M]

I would have loved to keep mine but economics got the better of me. I tried to find spiders but could only find used ones. My axle splines and spiders were worn but the ring and pinion were in good shape.
Apart from the cost and lack of parts other downsides are the bolt holes go right through the case and therefore are exposed to oil, this is the source for a lot of leaks. Put sealer on all the bolt threads and it seals up good.

[DennyB]

I dont think I can add much else to whats been said except, this is the rear that the 9" ford was modeled after.
Alot of pros search out these rears.
The fella that bought the factory locker I had said that there is a co. that take the lockers center section and rebuilds them for racers. The 10 bolt has a ring gear that is over 10" in diameter! Its not as "thick" as a ford-9", but is plenty strong.
ENJOY!

Denny

[D.PASSMORE]

I THINK US GEAR CUTS REPLACEMENT GEARS AND OFFERS A COMPLETE REBUILD KIT. COMES WITH THE ANCIENT PRELOAD
BEARING SET UP. HAD A GUY REBUILD MINE WITH THE ABOVE KIT , PUT A DETROIT POSI LOCKER AND CHANGED TO LATE MODEL AXLES (MORE SPLINES). COST ME A FEW BUCKS , BUT IF ITS YOUR TRUCK AND A KEEPER. ITS WORTH IT. AFTER 15 K , NO CHANGE IN PERFORMANCE . NOW THE NP 205 NEEDS TO BE GONE THROUGH . VINCE, YOU KNOW ABOUT REBUILDING THEM . ANY TRICKS?

[COBALT]

Just to clarify lockers aren't posi units. Don't confuse them.

These will take a Detroit locker in replacement of the old spiders. Some of these had Eaton posi units in them as an option when they were first produced, but you can't get posi units for them now unless you go to someone who will either recondition old units, or make aftermarket ones. Spiders you can't get new unless (again) you go to someone specialized.