front and rear differential question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

CG · 07-24-2005, 09:35 PM

im in the process of locating a 3/4 ton front and rear diff for my 4x4. i have a couple of good leads. i ran across these today. its a 72 burb 3/4 ton. i think he said the gear ratio is 4/10. anyway, what are these called? they dont look like the 12 bolts on my other rigs and they dont look very heavy duty to me...thanks

Rod · 07-24-2005, 11:31 PM

That looks like 72 3/4 ton 4x4 axles to me from what I see. Plenty strong enough for the last 33 years.

CyberRanger · 07-25-2005, 12:05 AM

The left pic looks like the 3/4t Dana 44 front axle, although from that angle its a bit hard to tell. It'll carry the weight no problem, but won't handle a ton of power as the Dana 44 pinion & spider gears are a bit small for a truck this size. New Rubicon Wranglers run this same diff front & back.

The right pic is the GM Corporate (Eaton) 3/4t axle. As far as I know, parts are pretty hard to come by for it. It is seriously stout, but high mileage ones are difficult, if not impossible, to fix. I know of some going for over 500k miles before goin' south. I don't have a lot of experience w/ the Corp rear axles b/c I haven't seen many. The couple I did try to fix I couldn't get parts for. While the Dana 60 is easier to fix & parts are readily available, there are better rear axles for a 3/4t such as a Dana 70, Dana 80 or later model GM Corporate 14 bolts. I've seen many of the 60's spin the carrier bearings b/c the housing flexed or spread from too much power or too heavy a load. The later model 14 bolt axles are too long to look right IMHO, but I see a lot of trucks runnin' around w/ them unaltered.

CG · 07-25-2005, 01:12 AM

ive read threads that mention eaton/corporate rears but i didnt know what they were talking about. i can check the mileage on the burb they are in. basically im looking to update a 68 3/4 ton pickup to front disks. and pulling the front and rear out of the same truck will make sure they match correctly. i believe i was told i would have to move spring perches on anything newer than 72 on the rear. any off roading it will see will be light so im thinking going up to 14 bolt will be overkill. truck will be big block powered so maybe i should look at other options in between eaton and 14. no real hurry its going to be a year or so to put together...thanks for all the good info.

07-24-2005, 09:35 PM	#1
CG BlahBlahBlah Join Date: Feb 2002 Location: Wa. Posts: 19,843	front and rear differential question im in the process of locating a 3/4 ton front and rear diff for my 4x4. i have a couple of good leads. i ran across these today. its a 72 burb 3/4 ton. i think he said the gear ratio is 4/10. anyway, what are these called? they dont look like the 12 bolts on my other rigs and they dont look very heavy duty to me...thanks Attached Images

07-24-2005, 11:31 PM	#2
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	That looks like 72 3/4 ton 4x4 axles to me from what I see. Plenty strong enough for the last 33 years. __________________ Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife.

07-25-2005, 12:05 AM	#3
CyberRanger Registered User Join Date: Dec 2004 Location: North Central Colorado Posts: 38	The left pic looks like the 3/4t Dana 44 front axle, although from that angle its a bit hard to tell. It'll carry the weight no problem, but won't handle a ton of power as the Dana 44 pinion & spider gears are a bit small for a truck this size. New Rubicon Wranglers run this same diff front & back. The right pic is the GM Corporate (Eaton) 3/4t axle. As far as I know, parts are pretty hard to come by for it. It is seriously stout, but high mileage ones are difficult, if not impossible, to fix. I know of some going for over 500k miles before goin' south. I don't have a lot of experience w/ the Corp rear axles b/c I haven't seen many. The couple I did try to fix I couldn't get parts for. While the Dana 60 is easier to fix & parts are readily available, there are better rear axles for a 3/4t such as a Dana 70, Dana 80 or later model GM Corporate 14 bolts. I've seen many of the 60's spin the carrier bearings b/c the housing flexed or spread from too much power or too heavy a load. The later model 14 bolt axles are too long to look right IMHO, but I see a lot of trucks runnin' around w/ them unaltered. __________________ '71 K20 Custom Deluxe - 1 owner - Original 350 & 4 spd, Rams horn dual exhaust, Centerforce clutch, K&N 4"x15", factory tow hooks, 4" Skyjacker Softride, Rancho RSX9000s, custom Firestone AirRide overloads, 36" 305/85R16 10ply Buckshot Mudders, 4.11 gears

07-25-2005, 01:12 AM	#4
CG BlahBlahBlah Join Date: Feb 2002 Location: Wa. Posts: 19,843	ive read threads that mention eaton/corporate rears but i didnt know what they were talking about. i can check the mileage on the burb they are in. basically im looking to update a 68 3/4 ton pickup to front disks. and pulling the front and rear out of the same truck will make sure they match correctly. i believe i was told i would have to move spring perches on anything newer than 72 on the rear. any off roading it will see will be light so im thinking going up to 14 bolt will be overkill. truck will be big block powered so maybe i should look at other options in between eaton and 14. no real hurry its going to be a year or so to put together...thanks for all the good info.



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