GMC GM drop out thrid member REAR END ID question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

monzaz · 04-21-2010, 01:16 AM

Ok the drop out is a 1964 date code on the ring gear
AXLE spline is coarse
ring and pinion ratio trying to remember (8 on the pinion 36 on the ring ) 4.50 ratio??? maybe a few teeth off

Anyway it have a 10" ring gear + or - a 1/4" ish

has a bolt in pinion from the front like FORD 9" (5 bolts)

Ring gear bolts are on the inner diameter of the ring gear NOT in the traditional late model back side of the ring gear behind the ring gear teeth (IE 12 bolt chevy 10, bolt 8.5 etc. )

Does have the fifth bearing like a Ford 9" also BUT bigger.

Does this sound like a c30 c40 c50 c60 truck rear?

I have casting numbers i can get too if that helps. Jim

Thanks everyone

skoffice · 04-21-2010, 03:36 AM

I know a guy who used one of these in his rock crawler. I don't know much about them other than they did come in 3/4 ton pickups and up. Correct they are factory 4.56 gears, and from what I recall he had a hell of a time locating pinion bearings for it, or they were extremely expensive, I forgot. But that is a BAD A$$ rear end my friend. Wouldn't necessarily put it in anything 2wd but definitely a 4wd beast. I'm sure there are plenty of people on here that can tell you more.

monzaz · 04-21-2010, 07:58 AM

Yha they are MONSTER axles even though they are coarse.

SEEMS to be built like a TANK. Jim

This guy has it at his house and needs to unload the ring gear does have some slight chipped teeth but it is a locker.

So if you know of anyone wanting this let me know I will forward the phone number.

I will try to get pictures. Jim

skoffice · 04-21-2010, 09:05 AM

I don't really know of anyone needing one at the moment. I'd post something up in the 4x4 section or could be a good craigslist item. Forgot about the locker thats another plus to these axles

monzaz · 04-21-2010, 09:28 AM

Yah I just want to get as much info on it as possible so IF I have to ship someone does not say it is not what was listed correctly...lol. YOU know how that goes. Jim

**Captainfab** · 04-22-2010, 12:49 AM

What you are describing would be the Eaton HO52 or the HO72 rear differential. Yes they are tough as h**l and parts are hard to find and/or expensive.

monzaz · 04-22-2010, 02:51 PM

How can I tell if it is a locker or not? any place to look with out tearing open the carrier? Jim

**Captainfab** · 04-22-2010, 11:45 PM

With the trans in neutral, jack up one side and try and turn the wheel. If you can turn it , it is an open diff. If you can't turn it, it has a detroit locker.

monzaz · 04-23-2010, 07:23 AM

LOL...You're a funny guy... I only have the chunk...No truck No rear housing... If I am looking at the casrrier How do I tell?

All parts are incased in the carrier unit, spiders can not be seen etc.

Are there clutches of number or can some one post a picture of a locker unit out of the housing with the tell tale signs? :0 Thanks much. Jim

04-21-2010, 01:16 AM	#1
monzaz Registered User Join Date: Jan 2010 Location: Richfield, Oh Posts: 5	GMC GM drop out thrid member REAR END ID question Ok the drop out is a 1964 date code on the ring gear AXLE spline is coarse ring and pinion ratio trying to remember (8 on the pinion 36 on the ring ) 4.50 ratio??? maybe a few teeth off Anyway it have a 10" ring gear + or - a 1/4" ish has a bolt in pinion from the front like FORD 9" (5 bolts) Ring gear bolts are on the inner diameter of the ring gear NOT in the traditional late model back side of the ring gear behind the ring gear teeth (IE 12 bolt chevy 10, bolt 8.5 etc. ) Does have the fifth bearing like a Ford 9" also BUT bigger. Does this sound like a c30 c40 c50 c60 truck rear? I have casting numbers i can get too if that helps. Jim Thanks everyone

04-21-2010, 03:36 AM	#2
skoffice Registered User Join Date: Apr 2007 Location: Elk Grove, CA Posts: 375	Re: GMC GM drop out thrid member REAR END ID question I know a guy who used one of these in his rock crawler. I don't know much about them other than they did come in 3/4 ton pickups and up. Correct they are factory 4.56 gears, and from what I recall he had a hell of a time locating pinion bearings for it, or they were extremely expensive, I forgot. But that is a BAD A$$ rear end my friend. Wouldn't necessarily put it in anything 2wd but definitely a 4wd beast. I'm sure there are plenty of people on here that can tell you more. __________________ 1964 C10 Shortened Shortbed Cammed LQ9 P&P 1967 C10 Trophy Truck BB 438 (soon to be worked on again)

04-21-2010, 07:58 AM	#3
monzaz Registered User Join Date: Jan 2010 Location: Richfield, Oh Posts: 5	Re: GMC GM drop out thrid member REAR END ID question Yha they are MONSTER axles even though they are coarse. SEEMS to be built like a TANK. Jim This guy has it at his house and needs to unload the ring gear does have some slight chipped teeth but it is a locker. So if you know of anyone wanting this let me know I will forward the phone number. I will try to get pictures. Jim

04-21-2010, 09:05 AM	#4
skoffice Registered User Join Date: Apr 2007 Location: Elk Grove, CA Posts: 375	Re: GMC GM drop out thrid member REAR END ID question I don't really know of anyone needing one at the moment. I'd post something up in the 4x4 section or could be a good craigslist item. Forgot about the locker thats another plus to these axles __________________ 1964 C10 Shortened Shortbed Cammed LQ9 P&P 1967 C10 Trophy Truck BB 438 (soon to be worked on again)

04-21-2010, 09:28 AM	#5
monzaz Registered User Join Date: Jan 2010 Location: Richfield, Oh Posts: 5	Re: GMC GM drop out thrid member REAR END ID question Yah I just want to get as much info on it as possible so IF I have to ship someone does not say it is not what was listed correctly...lol. YOU know how that goes. Jim

04-22-2010, 12:49 AM	#6
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,250	Re: GMC GM drop out thrid member REAR END ID question What you are describing would be the Eaton HO52 or the HO72 rear differential. Yes they are tough as h**l and parts are hard to find and/or expensive. __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE

04-22-2010, 02:51 PM	#7
monzaz Registered User Join Date: Jan 2010 Location: Richfield, Oh Posts: 5	Re: GMC GM drop out thrid member REAR END ID question How can I tell if it is a locker or not? any place to look with out tearing open the carrier? Jim

04-22-2010, 11:45 PM	#8
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,250	Re: GMC GM drop out thrid member REAR END ID question With the trans in neutral, jack up one side and try and turn the wheel. If you can turn it , it is an open diff. If you can't turn it, it has a detroit locker. __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE

04-23-2010, 07:23 AM	#9
monzaz Registered User Join Date: Jan 2010 Location: Richfield, Oh Posts: 5	Re: GMC GM drop out thrid member REAR END ID question LOL...You're a funny guy... I only have the chunk...No truck No rear housing... If I am looking at the casrrier How do I tell? All parts are incased in the carrier unit, spiders can not be seen etc. Are there clutches of number or can some one post a picture of a locker unit out of the housing with the tell tale signs? :0 Thanks much. Jim



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