rear end question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Robznob11 · 03-02-2007, 03:48 PM

how do i identify my rear end carrier with out totally disasembeling my rear end. i have the cover off but i know there is a 3 and a 4 series carrier and i need to know if there is a simple way to identify them...

71chevylowrider · 03-02-2007, 03:59 PM

Here's the number on a series 4 carrier

Robznob11 · 03-02-2007, 04:18 PM

well its hard to see the pinion but the ring gear has 41 teeth its an open diff 12 bolt short bed truck that had a 6 cyl orginal

71chevylowrider · 03-02-2007, 04:20 PM

So? If it's an open carrier then it's not a series 4 posi then. The picture i posted is a series 4 posi carrier.

71chevylowrider · 03-02-2007, 04:24 PM

Does your glovebox have the tag on it? I found a chart that shows what the RPO codes mean.

71chevylowrider · 03-02-2007, 04:27 PM

I'm no expert, but just from what I know a 41 tooth ring gear is gonna be either a 3.42, a 3.73, or a 4.56

If you have a tach & it was drivable, I have a chart that can tell you what you have if you know your RPM's at 60 MPH & you need your tire height in inch's

Robznob11 · 03-02-2007, 04:30 PM

yea mine says 3866116n, i new it was not a posi i just did not know if it could be replaced with eather 3 or 4 series if i have to change all the guts or what. all i know is that i want to have a posi 3.73 witch will require a 3 series but i would settel for a 4.10 with a 4 series if it would fit. if you know much about this tell me what i need to do to get what im after...

71chevylowrider · 03-02-2007, 04:52 PM

3.73 is the dividing point, series 3 goes up to 3.73, & series 4 starts from 3.73, so that may help you decide which carrier, all I know is I wouldn't take on the task of exchanging rear end gear carriers unless I really knew what i was up against, there's the shims, the backlash, making sure the teeth run in the center . I've been told it would be alot easier to find another rearend that had Posi in it, & swap the whole thing out, yours being a 67, there is the dillema of will a 70 & 1/2 to 72 rearend fit? They are a little wider, but some guys on here have done it & are still driving it, I think there is something about using later model truck calipers maybe?

71chevylowrider · 03-02-2007, 04:57 PM

I only know all this stuff cause I've been searching for an Eaton series 4 posi for about 6 months now, so I can tell the difference between a series 3 & a 4

here's a used sereis 4 for sale on evilbay

http://cgi.ebay.com/ebaymotors/12-BO...ayphotohosting

Orange · 03-02-2007, 05:11 PM

Ring Gear Teeth/Pinion Gear Teeth = Rear End Ratio (if that'll help you any).

Mine was a 3.07 (43 ring gear teeth and 14 pinion gear teeth I think)

43/14=3.07

DLB

71chevylowrider · 03-02-2007, 05:21 PM

Yep, & a 41 with an 11 is a 3.73 gear

03-02-2007, 03:48 PM	#1
Robznob11 Registered User Join Date: Feb 2004 Location: brownfield texas (west texas) Posts: 1,936	rear end question how do i identify my rear end carrier with out totally disasembeling my rear end. i have the cover off but i know there is a 3 and a 4 series carrier and i need to know if there is a simple way to identify them... __________________ The Ghost 67 short wide full custom. 550 hp LSX, 4l80E, narrowed 9". Body dropped w/air ride! ........................ ___ .........________//__{\_____ ,,,,,,,/__(⊙)___//___/__(O)_/ @disciple2.rc 💪instagram💪 LED TAILS

03-02-2007, 03:59 PM	#2
71chevylowrider Senior Member Join Date: Sep 2006 Location: Vancouver, WA Posts: 1,015	Re: rear end question Here's the number on a series 4 carrier Attached Images

03-02-2007, 04:18 PM	#3
Robznob11 Registered User Join Date: Feb 2004 Location: brownfield texas (west texas) Posts: 1,936	Re: rear end question well its hard to see the pinion but the ring gear has 41 teeth its an open diff 12 bolt short bed truck that had a 6 cyl orginal __________________ The Ghost 67 short wide full custom. 550 hp LSX, 4l80E, narrowed 9". Body dropped w/air ride! ........................ ___ .........________//__{\_____ ,,,,,,,/__(⊙)___//___/__(O)_/ @disciple2.rc 💪instagram💪 LED TAILS

03-02-2007, 04:20 PM	#4
71chevylowrider Senior Member Join Date: Sep 2006 Location: Vancouver, WA Posts: 1,015	Re: rear end question So? If it's an open carrier then it's not a series 4 posi then. The picture i posted is a series 4 posi carrier.

03-02-2007, 04:24 PM	#5
71chevylowrider Senior Member Join Date: Sep 2006 Location: Vancouver, WA Posts: 1,015	Re: rear end question Does your glovebox have the tag on it? I found a chart that shows what the RPO codes mean.

03-02-2007, 04:27 PM	#6
71chevylowrider Senior Member Join Date: Sep 2006 Location: Vancouver, WA Posts: 1,015	Re: rear end question I'm no expert, but just from what I know a 41 tooth ring gear is gonna be either a 3.42, a 3.73, or a 4.56 If you have a tach & it was drivable, I have a chart that can tell you what you have if you know your RPM's at 60 MPH & you need your tire height in inch's

03-02-2007, 04:30 PM	#7
Robznob11 Registered User Join Date: Feb 2004 Location: brownfield texas (west texas) Posts: 1,936	Re: rear end question yea mine says 3866116n, i new it was not a posi i just did not know if it could be replaced with eather 3 or 4 series if i have to change all the guts or what. all i know is that i want to have a posi 3.73 witch will require a 3 series but i would settel for a 4.10 with a 4 series if it would fit. if you know much about this tell me what i need to do to get what im after... __________________ The Ghost 67 short wide full custom. 550 hp LSX, 4l80E, narrowed 9". Body dropped w/air ride! ........................ ___ .........________//__{\_____ ,,,,,,,/__(⊙)___//___/__(O)_/ @disciple2.rc 💪instagram💪 LED TAILS

03-02-2007, 04:52 PM	#8
71chevylowrider Senior Member Join Date: Sep 2006 Location: Vancouver, WA Posts: 1,015	Re: rear end question 3.73 is the dividing point, series 3 goes up to 3.73, & series 4 starts from 3.73, so that may help you decide which carrier, all I know is I wouldn't take on the task of exchanging rear end gear carriers unless I really knew what i was up against, there's the shims, the backlash, making sure the teeth run in the center . I've been told it would be alot easier to find another rearend that had Posi in it, & swap the whole thing out, yours being a 67, there is the dillema of will a 70 & 1/2 to 72 rearend fit? They are a little wider, but some guys on here have done it & are still driving it, I think there is something about using later model truck calipers maybe?

03-02-2007, 04:57 PM	#9
71chevylowrider Senior Member Join Date: Sep 2006 Location: Vancouver, WA Posts: 1,015	Re: rear end question I only know all this stuff cause I've been searching for an Eaton series 4 posi for about 6 months now, so I can tell the difference between a series 3 & a 4 here's a used sereis 4 for sale on evilbay http://cgi.ebay.com/ebaymotors/12-BO...ayphotohosting

03-02-2007, 05:11 PM	#10
Orange Licensed to Thrill! Join Date: Apr 2006 Location: Northwest, GA Posts: 1,673	Re: rear end question Ring Gear Teeth/Pinion Gear Teeth = Rear End Ratio (if that'll help you any). Mine was a 3.07 (43 ring gear teeth and 14 pinion gear teeth I think) 43/14=3.07 DLB __________________ 1971 GMC.Lowered. Overdrive. Orange. Krue's excellent FAQ Index. Last edited by Orange; 03-02-2007 at 05:12 PM.

03-02-2007, 05:21 PM	#11
71chevylowrider Senior Member Join Date: Sep 2006 Location: Vancouver, WA Posts: 1,015	Re: rear end question Yep, & a 41 with an 11 is a 3.73 gear

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