Rear end gears - The 1947 - Present Chevrolet & GMC Truck Message Board Network

MARIOS68PANEL · 04-29-2005, 09:04 PM

I beleive I have 4.11 gears . PO told me they were and at 55 the engine is wound up tight. Dont have a tach so I`m not sure of the rpm`s. I think I should go to 3.73`s for the milage .I do more open road driveing that intown. How much should a good set of 3.73`s cost me or should I be able to trade mine for a set? are all 4.11 gears posi? thanks

**COBALT** · 04-29-2005, 11:37 PM

This ALL depends on what type of rear-end differential you have. Can you describe it? What does it look like? Can you go as far as snapping some pics?

**pjmoreland** · 04-30-2005, 12:54 AM

If you do more highway driving, I'd recommend 3.07 or 3.42 gears. There isn't a huge difference between 4:11 and 3.73.

You're probably looking at somewhere between $165 and $200 for a gearset.

Here's a link for 12-bolt rear end gearsets:

http://store.summitracing.com/defaul...=egnsearch.asp

MARIOS68PANEL · 04-30-2005, 12:59 AM

It`s the original 12 bolt 4.11 posi (so I was told)that was in the Panel when I bought it. It is 12 bolt smokes both wheels when I get on it. And at 55 it`s wound tight
I dont have it tore apart. So pic`s wouldnt do any good.

flip66 · 04-30-2005, 01:59 AM

Some one correct me if I am wrong but don’t 4:11 to 3:73 use a different carrier then the 3:07 to 3:42. If you go with anything 3:42 or taller you will need a different carrier.

*Tanker350* · 04-30-2005, 03:15 AM

You're gona need a 4 series carrier. I replaced mine to a 3.73 Posi unit, new gears, bearings, and install kit.

Longhorn Man · 04-30-2005, 06:14 AM

I would day find a 3.07 rear end out of another truck, and slap the whole thing in. Then you can cruise with good RPM's. This was with a 350?TH350 and 28 inch tall tires out back

No, not all 4:10 or 4:11 rears were posi, they were seperate options.

PanelDeland · 04-30-2005, 08:28 AM

Most of the panels came with the 3:73 gear.That's not to say yours doesn't have the 4:11 but befor you get all excited you need to check your ratio.Just jack up a wheel and mark the tire and driveshaft.Rotate the driveshaft one full turn and you should be able to count the revolutions of the tire.This will tell you the ratio.If you have a 6cyl it will sound wound at 55-60 with either gear.Someone should post a formula for gear and tire sizes or maybe they're in FAQ's.I can't find mine at the moment.This will give you a good idea of what you have and a better idea of where you want tto go.
I'm just saying you need to know where you are befor the map can help you get there.

Paul72 · 04-30-2005, 08:52 AM

Thanks for the research, Andy! Don't go killing yourself, snapping pictures at 90 mph.....

I can hear you now - "No really, officer, I was just trying to help someone else! That was the first time I've ever gone faster than 60 in my life......"

MARIOS68PANEL · 04-30-2005, 01:01 PM

Yeah, what he said. No killing yourself . Thanks longhorn, A local shop guy told me if I had 4:11`s it had to be posi. Im perty sure mine are but I thought he was bs`en me .Panel Deland , It now has a 305 v8 th350 so I was thinking it shouldnt be so wound up.I will try the tire off the ground thing later today and see what she says. Thanks to all for info

04-29-2005, 09:04 PM	#1
MARIOS68PANEL Active Member Join Date: Mar 2005 Location: North Highlands. California Posts: 449	Rear end gears I beleive I have 4.11 gears . PO told me they were and at 55 the engine is wound up tight. Dont have a tach so I`m not sure of the rpm`s. I think I should go to 3.73`s for the milage .I do more open road driveing that intown. How much should a good set of 3.73`s cost me or should I be able to trade mine for a set? are all 4.11 gears posi? thanks __________________ 67 short step 71 Custom

04-29-2005, 11:37 PM	#2
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	This ALL depends on what type of rear-end differential you have. Can you describe it? What does it look like? Can you go as far as snapping some pics? __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

04-30-2005, 12:54 AM	#3
pjmoreland Senior Member Join Date: Jan 2005 Location: CA Posts: 6,004	If you do more highway driving, I'd recommend 3.07 or 3.42 gears. There isn't a huge difference between 4:11 and 3.73. You're probably looking at somewhere between $165 and $200 for a gearset. Here's a link for 12-bolt rear end gearsets: http://store.summitracing.com/defaul...=egnsearch.asp Last edited by pjmoreland; 04-30-2005 at 12:58 AM.

04-30-2005, 12:59 AM	#4
MARIOS68PANEL Active Member Join Date: Mar 2005 Location: North Highlands. California Posts: 449	It`s the original 12 bolt 4.11 posi (so I was told)that was in the Panel when I bought it. It is 12 bolt smokes both wheels when I get on it. And at 55 it`s wound tight I dont have it tore apart. So pic`s wouldnt do any good. __________________ 67 short step 71 Custom

04-30-2005, 01:59 AM	#5
flip66 Registered User Join Date: Jan 2004 Location: Garland TX Dallas area Posts: 658	Some one correct me if I am wrong but don’t 4:11 to 3:73 use a different carrier then the 3:07 to 3:42. If you go with anything 3:42 or taller you will need a different carrier. __________________ 1998 Pontiac Grad Prix GTP 1969 C10 396 TH400 3.08 posi

04-30-2005, 03:15 AM	#6
Tanker350 Account Suspended Join Date: Dec 2003 Location: Palm Desert, Ca Posts: 410	You're gona need a 4 series carrier. I replaced mine to a 3.73 Posi unit, new gears, bearings, and install kit.

04-30-2005, 06:14 AM	#7
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	I would day find a 3.07 rear end out of another truck, and slap the whole thing in. Then you can cruise with good RPM's. This was with a 350?TH350 and 28 inch tall tires out back No, not all 4:10 or 4:11 rears were posi, they were seperate options.

04-30-2005, 08:28 AM	#8
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,992	Most of the panels came with the 3:73 gear.That's not to say yours doesn't have the 4:11 but befor you get all excited you need to check your ratio.Just jack up a wheel and mark the tire and driveshaft.Rotate the driveshaft one full turn and you should be able to count the revolutions of the tire.This will tell you the ratio.If you have a 6cyl it will sound wound at 55-60 with either gear.Someone should post a formula for gear and tire sizes or maybe they're in FAQ's.I can't find mine at the moment.This will give you a good idea of what you have and a better idea of where you want tto go. I'm just saying you need to know where you are befor the map can help you get there. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

04-30-2005, 08:52 AM	#9
Paul72 Registered User Join Date: Sep 2003 Location: Waterloo, IA Posts: 1,147	Thanks for the research, Andy! Don't go killing yourself, snapping pictures at 90 mph..... I can hear you now - "No really, officer, I was just trying to help someone else! That was the first time I've ever gone faster than 60 in my life......" __________________ '72 Chevy K20 - 383/4sp/205 - SOLD after 41 years in the family Next project - K/5 Tahoe (71 Blazer on 99 Tahoe chassis) Build thread: http://67-72chevytrucks.com/vboard/s...d.php?t=789958 Last edited by Paul72; 04-30-2005 at 08:53 AM.

04-30-2005, 01:01 PM	#10
MARIOS68PANEL Active Member Join Date: Mar 2005 Location: North Highlands. California Posts: 449	Yeah, what he said. No killing yourself . Thanks longhorn, A local shop guy told me if I had 4:11`s it had to be posi. Im perty sure mine are but I thought he was bs`en me .Panel Deland , It now has a 305 v8 th350 so I was thinking it shouldnt be so wound up.I will try the tire off the ground thing later today and see what she says. Thanks to all for info __________________ 67 short step 71 Custom



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