Diff Ratio ID - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**'68OrangeSunshine** · 08-06-2010, 01:44 AM

I have a '72 K/5 parts truck. I want to cannibalize the rear axle for a replacement on my '71 Jimmy 4x4. I pulled the differential cover and read off the following numbers:
326663
N
GM 34
3817779
14:43
GM 09752
015 [hand stamped]
This is an open diff 12 bolt.
We turned the tire about 3 times for one turn of the ring gear.
I'm guessing 3.07:1,
I was hoping for a 3.73:1 for a direct replacement. I might get by with the 3.07 temporarily while I rebuild the 3.73 Posi, if I disconnect the front prop shaft so I [or someone else who is not familiar with the swap] don't accidently shift into 4WD and tear up the driveline and/or transfer case.

Redcap · 08-06-2010, 01:49 AM

Quote:

Originally Posted by '68OrangeSunshine

I have a '72 K/5 parts truck. I want to cannibalize the rear axle for a replacement on my '71 Jimmy 4x4. I pulled the differential cover and read off the following numbers:
326663
N
GM 34
3817779
14:43
GM 09752
015 [hand stamped]
This is an open diff 12 bolt.
We turned the tire about 3 times for one turn of the ring gear.
I'm guessing 3.07:1,
I was hoping for a 3.73:1.

43 divided by 14 is 3.07.

**'68OrangeSunshine** · 08-08-2010, 04:31 AM

Well maybe I'll swap out the axle for something that works. I did the math after I posted. As I recall. I once read 41.11 on a ring gear and assumed it meant it was a 4.11 rear. But a real machanic said I had to divide. So 11 into 41 is 3.7272727 = 3.73, then 14 into 43 = 3.0714286 :. 3.07.
I have a downed '67 K/10 Suburban with a 12-bolt 3.73 and auburn posi that I had rebuilt in the mid '90s. May be the best candidate. Putting a 3.07 rear on a 4x4 with a 3.73 D44 front is asking for trouble.

msgross · 08-08-2010, 07:50 PM

yeah, that would make for a rough ride!

08-06-2010, 01:44 AM	#1
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,022	Diff Ratio ID I have a '72 K/5 parts truck. I want to cannibalize the rear axle for a replacement on my '71 Jimmy 4x4. I pulled the differential cover and read off the following numbers: 326663 N GM 34 3817779 14:43 GM 09752 015 [hand stamped] This is an open diff 12 bolt. We turned the tire about 3 times for one turn of the ring gear. I'm guessing 3.07:1, I was hoping for a 3.73:1 for a direct replacement. I might get by with the 3.07 temporarily while I rebuild the 3.73 Posi, if I disconnect the front prop shaft so I [or someone else who is not familiar with the swap] don't accidently shift into 4WD and tear up the driveline and/or transfer case. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not. Last edited by '68OrangeSunshine; 08-06-2010 at 01:51 AM.

08-08-2010, 04:31 AM	#3
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,022	Re: Diff Ratio ID Well maybe I'll swap out the axle for something that works. I did the math after I posted. As I recall. I once read 41.11 on a ring gear and assumed it meant it was a 4.11 rear. But a real machanic said I had to divide. So 11 into 41 is 3.7272727 = 3.73, then 14 into 43 = 3.0714286 :. 3.07. I have a downed '67 K/10 Suburban with a 12-bolt 3.73 and auburn posi that I had rebuilt in the mid '90s. May be the best candidate. Putting a 3.07 rear on a 4x4 with a 3.73 D44 front is asking for trouble. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not. Last edited by '68OrangeSunshine; 08-08-2010 at 04:34 AM.

08-08-2010, 07:50 PM	#4
msgross Registered User Join Date: Jul 2006 Location: Central PA Posts: 12,201	Re: Diff Ratio ID yeah, that would make for a rough ride! __________________ The Garage: 1968 K-10 SWB - "Project Money Pit" 1996 Z-71 - "huntin rig" 1969 C-10 LWB (SOLD) "Project flip that truck or else" 1993 Passport, F@rd 1-ton (SOLD)"Project Cousin Eddie" My Garage Build "The 1,000 footer"



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