What axle do I have?

[72_Chev_Truck]

I have a 72' 3/4 ton with 8 bolt wheels and coil spring suspension. what axle do I have underneath?

[Jeremy_5]

I would need a pic, but I would assume a Dana 60.

If it is a dana 60 it will have the number "60" stamped on it.

[Jeremy_5]

does it look like this? This is mine out of a 72 3/4 ton.

[JIMs70GMC]

Either a dana 60 as was said or a corperate axle refered to as the "eaton" and also refered to by it's RPO # H052. The H052 has a round cover and drop out center section.

[72_Chev_Truck]

I think my rear cover is completely smooth

[Rod]

This is what the basic corporation aka. eaton diff looks like.

[COBALT]

...wow that's a purdy axle.

The classic "round cover" axle confuses a lot of people who first get into these trucks. A lot of people call them "eaton" axles, which they're not. Eaton made the carrier. Spicer made the pinion yoke and other components, and GM made the housing (why others call it a "corporate" axle). Some came with time-bomb governor lockers, others with the standard carrier, while a few came with an eaton posi (which are extremely hard to find). The gear sets were typically 4.10, 4.56, and even as high as in the 5's. I remember seeing one set of 3.73 gears, but since then everyone tells me they never existed, and I'm full of crap. Needless to say someone had a set, and wouldn't sell them to me, so...I think they did exist at one time. For a while a few years ago you could get brand new 3.90 gears for them, but not any more...They're all coil sprung. Although their bigger brothers (HO72) are leaf sprung for 1 tons. BUT (and here's more confusion) a lot of part manufacturers would ID HO52 axles the same as HO72 REGARDLESS of how the suspension was configured, so an axle shop would probably tell you all of their books say it's an HO72. Period.

First, the numbers on the housing are close to worthless. Second there's distinct differences between 3/4 ton and 1 ton in this veriety as mentioned before. Third, there's no way in hell to get parts for them any more unless you can find some used ones. Usually you see these axles ripped out and Dana axles put in their place.

Both of my trucks have HO52 axles under them. One was rebuilt a few years ago while the other is still rotting away under the truck. The rebuilt one now sports a detroit locker in the carrier (now no longer available - sorry), and 3.90 gears versus the 4.10s that originally came with it (also no longer available).

The original carriers were great, but the housing had a tendancy to leak at the cover bolts over time, which means dirt and other contaminates could get in. Leaking meant oil would seep out and force the bearings to start to heat up if the fluid level wasn't checked and the housing flushed. Over long periods these giant bearing sets would ultimately seize up - turning the whole thing into a loud squealing mess. The carrier would start to fight the gear set, and the spiders inside the carrier were weak. They would break, and ruin the gear set. Now you have a 500 lb hunk of dirty metal to throw away...

If you have one keep it clean. Keep it sealed, and inspect it every once in a while to see how it's wearing. Buy a new cap for it if you still have the original, and FORGET about trying to find a gasket for it. Use some RTV (Copper or Black), or some Sillicone II window/door sealer to seal it up. Seal up the bolts before you put them back in.

If it looks like it's going to be trouble start planning on your axle swap ahead of time.

[COBALT]

I think the 3.90 gears may still be available:

http://www.ringpinion.com/content/pr...id=285&rid=125

[Edmond]

So Cobalt, if I wanted to change the axle from my 1971 3/4 ton Longhorn,
which ones can I use to do the swap?
And is this a straight forward job to do?
Thanks!

Cya,
Edmond

[COBALT]

I've never done an axle swap, but I've had my axle out of the truck to rebuild the rear suspension, and based on what I learned from that:

1. You need to think about your pinion size to your new axle, and length. The HO52 is a big axle. You may need a different driveshaft.

2. You have to think about suspension. If it's set up for a coil suspension you may only need new U bolts for your trailing arms. If you have leafs then you may be in for more trouble.

3. Inset to the wheels may be different due to the new axle length. This may mean thinking about new wheels and tire sizes.

4. You may have to worry about shock relocation, and whether or not your rear brake cables need to be redone, blah blah blah...

There are plenty of guys who have done axle swaps. Ask on the suspension board.

[JIMs70GMC]

I don't think they were all coil sprung, they did come in 4wds, which are leaf sprung. My 1970 chassis book has the only difference between the two H052 and H072 is the size of the brakes 12x2 vs. 13x2. The 72 c30 in my signature has a gross rear axle rating of 11000 lbs.
Some axles have a ring gear deflection bolt. Also the carriers could either be 2 pinion or 4 pinion variety.

[Longhorn Man]

COBALT, very good info. However, like Jim said, there were some leaf sprung HO52...had one under the old CST/20 Longhorn I used to have.

[crew70]

I have a HO52 in my 70 3/4 ton 4x4. leaf springs and all.what do you mean they only come in coil overs ? every 3/4 ton 4x4 I have had has had a HO52. the only truck that
I have had with a HO72 was a camper (1 ton) and the carrier was the same but the brakes were bigger and every one I have talked to that biulds rearends says that they good and tuff.but very expensive to fix.I had no problem finding parts for it two
years ago.

[1969 GMC]

Originally Posted by COBALT

...wow that's a purdy axle.

The classic "round cover" axle confuses a lot of people who first get into these trucks. A lot of people call them "eaton" axles, which they're not. Eaton made the carrier. Spicer made the pinion yoke and other components, and GM made the housing (why others call it a "corporate" axle). Some came with time-bomb governor lockers, others with the standard carrier, while a few came with an eaton posi (which are extremely hard to find). The gear sets were typically 4.10, 4.56, and even as high as in the 5's. I remember seeing one set of 3.73 gears, but since then everyone tells me they never existed, and I'm full of crap. Needless to say someone had a set, and wouldn't sell them to me, so...I think they did exist at one time. For a while a few years ago you could get brand new 3.90 gears for them, but not any more...They're all coil sprung. Although their bigger brothers (HO72) are leaf sprung for 1 tons. BUT (and here's more confusion) a lot of part manufacturers would ID HO52 axles the same as HO72 REGARDLESS of how the suspension was configured, so an axle shop would probably tell you all of their books say it's an HO72. Period.

First, the numbers on the housing are close to worthless. Second there's distinct differences between 3/4 ton and 1 ton in this veriety as mentioned before. Third, there's no way in hell to get parts for them any more unless you can find some used ones. Usually you see these axles ripped out and Dana axles put in their place.

Both of my trucks have HO52 axles under them. One was rebuilt a few years ago while the other is still rotting away under the truck. The rebuilt one now sports a detroit locker in the carrier (now no longer available - sorry), and 3.90 gears versus the 4.10s that originally came with it (also no longer available).

The original carriers were great, but the housing had a tendancy to leak at the cover bolts over time, which means dirt and other contaminates could get in. Leaking meant oil would seep out and force the bearings to start to heat up if the fluid level wasn't checked and the housing flushed. Over long periods these giant bearing sets would ultimately seize up - turning the whole thing into a loud squealing mess. The carrier would start to fight the gear set, and the spiders inside the carrier were weak. They would break, and ruin the gear set. Now you have a 500 lb hunk of dirty metal to throw away...

If you have one keep it clean. Keep it sealed, and inspect it every once in a while to see how it's wearing. Buy a new cap for it if you still have the original, and FORGET about trying to find a gasket for it. Use some RTV (Copper or Black), or some Sillicone II window/door sealer to seal it up. Seal up the bolts before you put them back in.

If it looks like it's going to be trouble start planning on your axle swap ahead of time.

The Eaton axles NEVER came with a gov lock, it was not used in GM trucks until the 70s. Some could have had the optional No-Spin, which is just the trade name for the Detroit Locker, which are very strong units. I have never seen nor heard of a posi available for this axle, so I can't say anything there.
I agree that there were never 3.73 gears...they aren't listed in any service manual I have been able to get my hands on. 4.11, 4.57, and 5.14 are the accepted norm, and I just found out recently there was a 5.83 set available (taken from the page of a Chevy TSM), but these are most likely impossible to find.
As others have pointed out...they are NOT all coil sprung.
The numbers in the third member are not all useless...on both of mine, they have part #'s as well as the gear ratio stamped into each.
You can still find parts for these, longhornman just had a post about finding brake guts. Of course you could buy a disc brake kit for the axle and be done with it, too. Bearings are still available, but they cost more because of their design.
I have never seen an axle that has had its shafts "ripped" out...when I took mine apart I just slid them out the ends. and I have never heard of one with dana axles put into it. 14 bolt, yes, dana, no.

as far as tearing up your carrier bearings...if you wouldnt let it get to the point that dirt could get inside the housing, you wouldnt have this problem, simple as that.

Pretty much the only thing I agree with is using RTV or silicone instead of a gasket for this axle. I kindly ask you to stop spouting lies and rubbish like this on the board.

[Robert1970C20rstbukt]

Also the pinion bearing on the 3/4 ton HO52's used sleeve bearings, and the1 ton HO72 used ball bearings. That's one small detail that's usually overlooked.

[Vince M]

I put a 1978 8 lug full floating 14 bolt in my 72 4x4 (leaf) and it is as close to a direct swap as you will find. I had to relocate the spring perches and shock mounts. If you have a welder and a grinder with a cutoff wheel you could do this swap easy. I didn't have to change the driveshaft and I reused the e-brake cables from the "Eaton".
I completely rebuilt the 14 bolt before installing and in my opinion it is a far superior axle to the "Eaton". Granted the "Eaton has some good points about it but overall the 14 bolt was easy to work on and wont leak like the "Eatons"' do. The axle spline count is higher, the brakes are larger (13"), all the bolts for covers and axle are blind holes, wide range of gears still available and parts, etc....etc...I could go on and on..

I replaced mine because the axle splines were wearing along with the spiders and I could only find used ones. I paid $100 for the 14 bolt and about $200 to rebuild it. You wont find "Eaton" parts for that price.

[COBALT]

Originally Posted by 1969 GMC

...as far as tearing up your carrier bearings...if you wouldnt let it get to the point that dirt could get inside the housing, you wouldnt have this problem, simple as that.

Pretty much the only thing I agree with is using RTV or silicone instead of a gasket for this axle. I kindly ask you to stop spouting lies and rubbish like this on the board.

Ok, so they're not all coil sprung. I always thought they were. That's a good thing to remember. Of course both of the trucks I have are almost identical, and I'm only reflecting on my own experience and what others have told me about these axles. I also thought that governor lockers made an appearance every once in a while..I remember hearing you could get a locker placed in the carrier as an option. More on this later. I hate to be defensive, but that's all I have to offer help. Since I didn't get much help when I was trying to do this I'm trying to give a guy a break...

The numbers on both of my housings didn't yield much information. The casting numbers didn't tell me much, and I never found a ratio anywhere. I've also found the original service manuals to be inaccurate on a lot of things from time to time. For instance the information on my dad's '67 wasn't right, because the dealership he bought it from brand new in Indiana offered trailer towing packages where they would modify the axle, and weld in hitches right there at the dealership. C10 trucks would sometimes end up with C20 components.

I strongly suspect there were aftermarket 3.73 gears available sometime in the last two decades. Who knows who made them, or whether or not they still exist somewhere. Probably not, but yes they were never made by GM. Maybe Yukon Gear. Maybe Spicer. Maybe maybe maybe...I just know I saw a set.

Finally, if it weren't for the smilie face at the end of your post I'd "kindly" tell you to kiss my a$$. I salvaged this truck out of a hayfield, so any intervention by me to keep the rear-end in good shape was prevented due to the bone-headed owner and gopher holes and cow pies around the axle tubes. But the next time I need some hand holding to find out how to keep dirt out of my differential I'll give you a buzz.

[JIMs70GMC]

My 1970 chassis manual shows ball bearings on the H110 and sleeve bearings on H052 and H072.

[Robert1970C20rstbukt]

Well OK, the HO52 and HO72 have sleeve bearings, and the heavy duty 11,000lb H110 axle has ball bearings. Thanks for the correction! The HO52 in my truck has sleeve bearings on the pinion, and the HO110 that I have from a 1 ton GMC has ball bearings. The one in my truck has the load bolt and so does the HO110. I thought only 1 ton rearends had that?

[COBALT]

You're talking about the deflection bolt in the drop-out member, right? Both of the HO52 axles have that.

[1969 GMC]

Originally Posted by Robert1970C20rstbukt

Well OK, the HO52 and HO72 have sleeve bearings, and the heavy duty 11,000lb H110 axle has ball bearings. Thanks for the correction! The HO52 in my truck has sleeve bearings on the pinion, and the HO110 that I have from a 1 ton GMC has ball bearings. The one in my truck has the load bolt and so does the HO110. I thought only 1 ton rearends had that?

The H110 is the "big" Eaton with the welded on diff cover and 12.25" ring gear. Do you have any pics of it? Don't think I've ever seen one under a light truck before.

As far as the load bolts go, not all of the Eatons have them. I don't know their rhyme or reason...my '66 C20 centersection does not have one, but the '67 or '68 C30 centersection does have one.

[Robert1970C20rstbukt]

Nope sorry don't have a pic of it. I don't have a dig. camera. I ain't really sure if it was original to the truck though. There were about 10 leaf springs and a helper spring pack on top of it that has about 8 or 10 leafs. I'm just guessing from memory, I don't remember exactly how many are on it. The rear end and the leaf springs are under a pile of scrap metal about 10 miles out from my house. That truck had some really damn tight suspension too. You could jump up and down on the bed and it would bearly even budge.

[crew70]

I like my HO52 because of its different and its original.It looks lust like the eatons in
the big trucks.If I was looking for some thing easy to work on and cheap I would swap it out.Its allways fun to have some one ask about them and here all the credible info some people have on them.

[JIMs70GMC]

If Hadn't sold my C30 i'd pull that sucker out and check it. The manual does have the ring gear deflection bolt for the H110 also.

[stllookn]

Ok...let me get this straight...the big round one (that looks like a F**D 9-in)in the 3/4 t. is a CORPORATE H052 (also coil spring) and the one with "60" cast into the cover is a DANA 60 (in both my 3/4 t. Longhorn leaf spring trucks).