Differential numbers decipher please - The 1947 - Present Chevrolet & GMC Truck Message Board Network

greenhorn male · 03-18-2005, 10:40 PM

It is a 14 bolt full floater pictured below. Only thing I know about it is, it is not stock to the 72 C20 it is bolted to right now. I would like to know the gear ratio and anything that you could share looking at the numbers and pictures. Thanks!

I took the numbers from the area pointed by the red arrow and they read: 1 GM 3977334 10 41 4 76

I plan on jacking it up sometime and count tire/driveshaft rotations but it is not on stable ground right now.

sdkid · 03-18-2005, 10:51 PM

1 GM 3977334 10 41 4 76
^ ^

41 divide by 10 is 4.10. 4 76 may be a date code(April 1976) I could be wrong.

greenhorn male · 03-18-2005, 11:38 PM

Quote:

Originally Posted by sdkid

1 GM 3977334 10 41 4 76
^ ^

41 divide by 10 is 4.10. 4 76 may be a date code(April 1976) I could be wrong.

Are you sure about the gear ratio?

**pjmoreland** · 03-19-2005, 03:46 AM

If you don't trust the numbers, count the teeth. You'll find 41 and 10 teeth on the two gears.

greenhorn male · 03-19-2005, 04:45 AM

I was just trying to confirm when sdkid said "I could be wrong", if he was just referring to the date code or his whole response.

Blazer1970 · 03-19-2005, 09:06 AM

sdkid is correct on the ratio and the date code.

1969 GMC · 03-19-2005, 06:06 PM

its also an open diff, which is good if you want to get a detroit locker for it.

greenhorn male · 03-19-2005, 08:37 PM

Thanks for all the information. This is great advise. I've always wondered what people meant by open differential.

03-18-2005, 10:40 PM	#1
greenhorn male Senior Member Join Date: Jan 2003 Location: Bay Area, Northern California Posts: 1,344	Differential numbers decipher please It is a 14 bolt full floater pictured below. Only thing I know about it is, it is not stock to the 72 C20 it is bolted to right now. I would like to know the gear ratio and anything that you could share looking at the numbers and pictures. Thanks! I took the numbers from the area pointed by the red arrow and they read: 1 GM 3977334 10 41 4 76 I plan on jacking it up sometime and count tire/driveshaft rotations but it is not on stable ground right now. Attached Images __________________ 03 Tahoe 72 GMC Super Custom 2500 Custom Camper, my reliable workhorse. Dual gauged tanks, dual battery trays. Last edited by greenhorn male; 03-18-2005 at 10:43 PM.

03-18-2005, 10:51 PM	#2
sdkid Registered User Join Date: Sep 2004 Location: Pierre SD Posts: 1,533	1 GM 3977334 10 41 4 76 ^ ^ 41 divide by 10 is 4.10. 4 76 may be a date code(April 1976) I could be wrong. __________________ I think the world needs a drink... Help somebody...If you can....VanZant We're not wrong, we're not sorry, and its probably gonna happen again. That's the truth about men. Tracy Byrd Member# 13924 '70 c10, 350/350 '68 c10 250/4spd '68 c10 no eng/trans fac ps/pb/ac/at (future father/sons project) '48 Chevy Loadmaster

03-19-2005, 04:45 AM	#5
greenhorn male Senior Member Join Date: Jan 2003 Location: Bay Area, Northern California Posts: 1,344	I was just trying to confirm when sdkid said "I could be wrong", if he was just referring to the date code or his whole response. __________________ 03 Tahoe 72 GMC Super Custom 2500 Custom Camper, my reliable workhorse. Dual gauged tanks, dual battery trays.

03-19-2005, 09:06 AM	#6
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,510	sdkid is correct on the ratio and the date code. __________________ Tim

03-19-2005, 06:06 PM	#7
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	its also an open diff, which is good if you want to get a detroit locker for it. __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650

03-19-2005, 03:46 AM	#4
pjmoreland Senior Member Join Date: Jan 2005 Location: CA Posts: 5,414	If you don't trust the numbers, count the teeth. You'll find 41 and 10 teeth on the two gears.

03-19-2005, 08:37 PM	#8
greenhorn male Senior Member Join Date: Jan 2003 Location: Bay Area, Northern California Posts: 1,344	Thanks Thanks for all the information. This is great advise. I've always wondered what people meant by open differential. __________________ 03 Tahoe 72 GMC Super Custom 2500 Custom Camper, my reliable workhorse. Dual gauged tanks, dual battery trays.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.