Eaton rear end - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Ace in the hole · 09-11-2007, 05:19 PM

I am new here, fairly good mechanically but never dealt with differentials. I know I have an eaton 3/4 ton leaf rear and I believe it has 4.56 gears but I have a couple of questions--

1- is this a posi?
2- I also have an eaton 3/4 ton coil rear end (inside looks the same as these pics), are internals the same? ie- can I use the second diff for parts if I need to?

Jcentsr6 · 09-11-2007, 05:26 PM

if the truck is on a lift...spin one rear wheel and see if the other spins the same way. If the tire spins the other way...its an open rear end.

Ace in the hole · 09-11-2007, 05:34 PM

I tried the spinning trick, the other wheel did not move either way.

jeffspower · 09-11-2007, 07:06 PM

No posi (clutch- type) was available for that rear end, but lockers were an option. I can see by the side gear that yours is just an std. differential. Yep, your coil spring 3rd member can be used.

71chevylowrider · 09-11-2007, 07:14 PM

Eaton Posi looks like this

Ace in the hole · 09-11-2007, 08:05 PM

Thanks guys.

wibilly · 09-11-2007, 08:11 PM

while that is a eaton posi that 71 chevy lowrider posted that is not the detroit locker that you will find in the eaton rear ends i didn't take a pic of mine so i can't post one up but they have no cluches in them. you will know if you have one because there are no spider gears in them

Ace in the hole · 09-11-2007, 10:29 PM

Ok, now you have me interested in what that would look like. Anybody with a pic of a eaton rear with a detroit locker?

Also, I am doing a complete tear down of this truck and was thinking of replacing the seals in the differentials (it's 4wd), thinking that 35 year old seals may be at the end of their service life but maybe I should just let well enough alone until they give me trouble. What do you guys think.

**special-K** · 09-12-2007, 06:11 AM

I`ll see about getting a picture of one out and apart that I have.12-bolts are Eaton`s,too,and that posi is from one of those.The 3/4t Eaton is known as the HO52 or Corporate rear,since Dana60s were also available.The 1t trucks used an HO72,same diff parts/bigger brakes & bearings(outer).

Blazer1970 · 09-12-2007, 06:46 AM

Actually, none of the axles discussed in this thread are Eatons. GM did use Eaton axles in the medium duty trucks, and those axles did look a lot like the GM Corporate HO52/HO72. The Eaton axles were big muthas with weight ratings of 18,500 lb and 23,000 lb.

All of the axles used in light trucks (HO52, HO72, 10 bolt, 12 bolt, etc.) except the Dana/Spicer models were made by a division of General Motors. That GM division was later spun off as American Axle and Manufacturing, and they still make almost all of the live axles used in GM vehicles.

If you go to a parts store asking for parts for an Eaton axle, you wont have a chance.

Ace in the hole · 09-12-2007, 07:08 AM

Good to know, thanks.
What about replacing the seals, good idea or just leave them until they start to leak?
Also, if I ever wanted to replace it with a dana, anything special I should look for?

Chris H · 09-12-2007, 11:21 AM

http://67-72chevytrucks.com/vboard/s...9&postcount=21

Ace in the hole · 09-12-2007, 04:04 PM

Thanks Chris, nice pics.

09-11-2007, 05:19 PM	#1
Ace in the hole Registered User Join Date: Apr 2007 Location: Kalamazoo, Michigan, USA Posts: 538	Eaton rear end I am new here, fairly good mechanically but never dealt with differentials. I know I have an eaton 3/4 ton leaf rear and I believe it has 4.56 gears but I have a couple of questions-- 1- is this a posi? 2- I also have an eaton 3/4 ton coil rear end (inside looks the same as these pics), are internals the same? ie- can I use the second diff for parts if I need to? __________________ 1970 K20, 350--- SOLD 05 silverado extended cab short box- duramax Jeep wrangler unlimited Last edited by Ace in the hole; 08-24-2008 at 10:10 PM.

09-11-2007, 05:26 PM	#2
Jcentsr6 Junior Member Join Date: Jul 2007 Location: Odenton, Md Posts: 552	Re: Eaton rear end if the truck is on a lift...spin one rear wheel and see if the other spins the same way. If the tire spins the other way...its an open rear end. __________________ going to sell this one...looking for a SWB project next.

09-11-2007, 05:34 PM	#3
Ace in the hole Registered User Join Date: Apr 2007 Location: Kalamazoo, Michigan, USA Posts: 538	Re: Eaton rear end I tried the spinning trick, the other wheel did not move either way. __________________ 1970 K20, 350--- SOLD 05 silverado extended cab short box- duramax Jeep wrangler unlimited

09-11-2007, 07:06 PM	#4
jeffspower Well, Whoop-dee-do! Join Date: Mar 2003 Location: Easton, Mo. pop.- me & scarcely a few others Posts: 2,302	Re: Eaton rear end No posi (clutch- type) was available for that rear end, but lockers were an option. I can see by the side gear that yours is just an std. differential. Yep, your coil spring 3rd member can be used. __________________ '68 GMC shortbox 4x4 350/SM465/T221- bought it in '83 SOLD '72 K20 500 Cad/TH400/NP205 SOLD '92 Chevy 2500 6.5 mech TD 4L80E crusty daily driver '72 Monte Carlo... sweet low mile toy '11 Dodge Challenger IE 392 6spd... midlife car

09-11-2007, 07:14 PM	#5
71chevylowrider Senior Member Join Date: Sep 2006 Location: Vancouver, WA Posts: 1,015	Re: Eaton rear end Eaton Posi looks like this Attached Images

09-11-2007, 08:05 PM	#6
Ace in the hole Registered User Join Date: Apr 2007 Location: Kalamazoo, Michigan, USA Posts: 538	Re: Eaton rear end Thanks guys. __________________ 1970 K20, 350--- SOLD 05 silverado extended cab short box- duramax Jeep wrangler unlimited

09-11-2007, 08:11 PM	#7
wibilly Senior Member Join Date: Nov 2005 Location: northwestern wi Posts: 2,111	Re: Eaton rear end while that is a eaton posi that 71 chevy lowrider posted that is not the detroit locker that you will find in the eaton rear ends i didn't take a pic of mine so i can't post one up but they have no cluches in them. you will know if you have one because there are no spider gears in them __________________ common sense isn't so common anymore

09-11-2007, 10:29 PM	#8
Ace in the hole Registered User Join Date: Apr 2007 Location: Kalamazoo, Michigan, USA Posts: 538	Re: Eaton rear end Ok, now you have me interested in what that would look like. Anybody with a pic of a eaton rear with a detroit locker? Also, I am doing a complete tear down of this truck and was thinking of replacing the seals in the differentials (it's 4wd), thinking that 35 year old seals may be at the end of their service life but maybe I should just let well enough alone until they give me trouble. What do you guys think. __________________ 1970 K20, 350--- SOLD 05 silverado extended cab short box- duramax Jeep wrangler unlimited

09-12-2007, 06:11 AM	#9
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,851	Re: Eaton rear end I`ll see about getting a picture of one out and apart that I have.12-bolts are Eaton`s,too,and that posi is from one of those.The 3/4t Eaton is known as the HO52 or Corporate rear,since Dana60s were also available.The 1t trucks used an HO72,same diff parts/bigger brakes & bearings(outer). __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

09-12-2007, 06:46 AM	#10
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,507	Re: Eaton rear end Actually, none of the axles discussed in this thread are Eatons. GM did use Eaton axles in the medium duty trucks, and those axles did look a lot like the GM Corporate HO52/HO72. The Eaton axles were big muthas with weight ratings of 18,500 lb and 23,000 lb. All of the axles used in light trucks (HO52, HO72, 10 bolt, 12 bolt, etc.) except the Dana/Spicer models were made by a division of General Motors. That GM division was later spun off as American Axle and Manufacturing, and they still make almost all of the live axles used in GM vehicles. If you go to a parts store asking for parts for an Eaton axle, you wont have a chance. __________________ Tim

09-12-2007, 07:08 AM	#11
Ace in the hole Registered User Join Date: Apr 2007 Location: Kalamazoo, Michigan, USA Posts: 538	Re: Eaton rear end Good to know, thanks. What about replacing the seals, good idea or just leave them until they start to leak? Also, if I ever wanted to replace it with a dana, anything special I should look for? __________________ 1970 K20, 350--- SOLD 05 silverado extended cab short box- duramax Jeep wrangler unlimited

09-12-2007, 11:21 AM	#12
Chris H 72 C30 Trailer Queen Join Date: Dec 1999 Location: SE MN, USA Posts: 794	Re: Eaton rear end http://67-72chevytrucks.com/vboard/s...9&postcount=21 __________________ Chris H 72 C30 133" 72 C30 157" flat-dump 69 C10 short fleet 71 ElCamino 2000 K2500 crewcab shortbed (sold, sorry old friend) 2005 GMC 2500HD shortcrew Duramax 2006 K1500 RCSB and a couple other projects/parts

09-12-2007, 04:04 PM	#13
Ace in the hole Registered User Join Date: Apr 2007 Location: Kalamazoo, Michigan, USA Posts: 538	Re: Eaton rear end Thanks Chris, nice pics. __________________ 1970 K20, 350--- SOLD 05 silverado extended cab short box- duramax Jeep wrangler unlimited

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