Rear end question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

toddtheodd · 10-19-2004, 08:40 AM

OK, I know that I have a 12 bolt. What I don't know is what a H052 or a H072 is.

Are they types of 12 bolts? Bigger (14) smaller (10) ???
Todd

**53burb** · 10-19-2004, 02:53 PM

They are Eaton RearEnds. I believe the HO52 or HO72 designates the gear ratio. They are usually found in 3/4ton and above trucks and Suburbans.

ckhd · 10-19-2004, 02:58 PM

An H052/H072 is a gm corporate heavy duty full floater axle. It hasn't been put under a pickup since 1972.

If you want to see what you have, take a peek at the back. If it looks like a big ol' round salad bowl, it's most likely a H052. The H072 is a heavier version of the h052. I don't know how to tell them apart from the outside. Has nothing to do with gear ratio. They also have a removable third member (like a Ford 9-inch, where you can drop the whole ring & pinion assembly out without disassembling them).

If you have a h052/h072, it's most likeley you have a 4.57 ratio, or lower (higher numerically)

If I remember right, the diff cover is held on by 10 bolts.

*FormerMember* · 10-19-2004, 03:16 PM

...

**JIMs70GMC** · 10-19-2004, 04:26 PM

The H052 and h072 have a diff cover(round w/ 10 bolts) and drop out center section similar to the ford 9". The difference between the h052 and H072 are the size of the brakes and the H072 has a bolt on the pinion to load the pinion bearings. As far as the differential inside they can either be 4 pinion or 2 pinion type in either axle. Also the H072 could have been a dually. Ring gear is 10.5" and the axles are right around 1.5" w/ 17 splines. The only traction device known is a detroit locker called a no-spin or no-slip I believe. Gear ratios are limited also; 4.10, 4.56 and 5.13 w/ an aftermarket 3.90 available. Here's a dually H072 in a 72 C30 I bought:

Longhorn Man · 10-19-2004, 04:36 PM

The HO72 will only be found under one tons, and only with leaf springs.
The HO52 is only under 3/4 tons, and can be leaf or coil.
As for gearing, the small block/automatic trucks automaticly got the 4.10 gears, which, combined with the stock sized tire is no worse than a 3.73 on a 1/2 ton. (Right around 3000 RPM for 70 MPH)

toddtheodd · 10-20-2004, 05:48 PM

So they are stronger / better than the 12 bolts?

**Yukon Jack** · 10-20-2004, 05:55 PM

Stronger, yes. Better, well, that depends on what you are going to use it for. Easier to get parts for a 12 bolt. Parts availability is the only downside to the Eaton in my opinion.

10-19-2004, 08:40 AM	#1
toddtheodd The oddest Todd around Join Date: May 2004 Location: Miami, Florida Posts: 1,418	Rear end question OK, I know that I have a 12 bolt. What I don't know is what a H052 or a H072 is. Are they types of 12 bolts? Bigger (14) smaller (10) ??? Todd

10-19-2004, 02:58 PM	#3
ckhd Registered User Join Date: Oct 2000 Location: St. Johns, Arizona Posts: 2,660	An H052/H072 is a gm corporate heavy duty full floater axle. It hasn't been put under a pickup since 1972. If you want to see what you have, take a peek at the back. If it looks like a big ol' round salad bowl, it's most likely a H052. The H072 is a heavier version of the h052. I don't know how to tell them apart from the outside. Has nothing to do with gear ratio. They also have a removable third member (like a Ford 9-inch, where you can drop the whole ring & pinion assembly out without disassembling them). If you have a h052/h072, it's most likeley you have a 4.57 ratio, or lower (higher numerically) If I remember right, the diff cover is held on by 10 bolts. __________________ my 2¢ - t.i.o.l.i. Bowen 1968 K20 fleet 1969 K10 swb fleet 1972 K10 Suburban 1972 C10 lwb step 1992 K1500 'burb 1995 K2500 'burb 1997 C1500 'burb 1999 K1500 2000 K1500 'burb Why do I own so many Suburbans?

10-19-2004, 03:16 PM	#4
FormerMember Account Suspended Join Date: Feb 2004 Posts: 3,051	... Last edited by FormerMember; 04-02-2009 at 03:55 PM.

10-19-2004, 04:26 PM	#5
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	The H052 and h072 have a diff cover(round w/ 10 bolts) and drop out center section similar to the ford 9". The difference between the h052 and H072 are the size of the brakes and the H072 has a bolt on the pinion to load the pinion bearings. As far as the differential inside they can either be 4 pinion or 2 pinion type in either axle. Also the H072 could have been a dually. Ring gear is 10.5" and the axles are right around 1.5" w/ 17 splines. The only traction device known is a detroit locker called a no-spin or no-slip I believe. Gear ratios are limited also; 4.10, 4.56 and 5.13 w/ an aftermarket 3.90 available. Here's a dually H072 in a 72 C30 I bought: __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm

10-20-2004, 05:55 PM	#8
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,686	Stronger, yes. Better, well, that depends on what you are going to use it for. Easier to get parts for a 12 bolt. Parts availability is the only downside to the Eaton in my opinion. __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

10-19-2004, 02:53 PM	#2
53burb Senior Member Join Date: May 2004 Location: Queen Creek, AZ Posts: 1,010	They are Eaton RearEnds. I believe the HO52 or HO72 designates the gear ratio. They are usually found in 3/4ton and above trucks and Suburbans.

10-19-2004, 04:36 PM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	The HO72 will only be found under one tons, and only with leaf springs. The HO52 is only under 3/4 tons, and can be leaf or coil. As for gearing, the small block/automatic trucks automaticly got the 4.10 gears, which, combined with the stock sized tire is no worse than a 3.73 on a 1/2 ton. (Right around 3000 RPM for 70 MPH)

10-20-2004, 05:48 PM	#7
toddtheodd The oddest Todd around Join Date: May 2004 Location: Miami, Florida Posts: 1,418	So they are stronger / better than the 12 bolts?

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