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Discussion Starter #1
How do I know if I've got a 3 series or a 4 series Carrier in my 12 bolt, It is presently complete, I havent taken it apart yet to find the ### on the carrier, but the gears are 4.10 GM, the part number is 3862526, is there any way of tell, without part numbers?? The code on the axle housing is QY, a 67 mono-leaf 12bolt with radius rod.

Thanks
 

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After 34+ years its hard to tell if factory or aftermarket. I believe 4.10's could be had on either if aftermarket.One way to know for sure.

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My '68 Camaro
Doug G.
68 Camaro
406 ci.
[email protected] W/ 2.73POSI.
 

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If memory serves me correctly a factory ordered 4:10 came with the series 4 carrier.
A later dealer swap got you the same gear with a spacer. I have one of those setups broken down in the garage.

Steve
 

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Factory 4.10 gears were on the 4 series differential. How did you get the number off of the gear if you didn't take the cover off? If you have the cover off the casting number on the differential case can be seen. It will be on the opposite side from the ring gear next to the bearing. The 3 series is EDB-30140 and the 4 series is EDB-30174.

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'69 RS/SS396 pro street
427/4spd/9"
Byars Performance
High Performance Drive Train Parts And Service
www.lubedealer.com/biggearhead
 

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Discussion Starter #6
Hi,

I had the cover ripped off, on the ring gear it reads:

2 GM 3862526 10 41 4 70

on the opposite side from the ring gear next to the bearing. It reads ED-30140PU1 So does this make sense? a 3 series carrier, but factory 4.10 gears...

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Discussion Starter #7
Also, the bearing cap/cover, whatever its called, has this number:

GM105 3858703N

I was a little hard to read,

Thanks
 

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You have a 4:10 gearset. I am guessing it was probably made in April 1970. If there is a shim about 5/16 thick between it and the flange on the carrier it is a series 3. If there is no shim its a series 4.

Steve
 

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The 30140 is a 3 series. It has to have a ring gear spacer in it. There is no other way you could have a GM 4.10 gear on a 3 series differential.

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'69 RS/SS396 pro street
427/4spd/9"
Byars Performance
High Performance Drive Train Parts And Service
www.lubedealer.com/biggearhead
 

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Discussion Starter #10
I want to post a pic, of it, but dont know how, so I will email you guys a pic of my carrier, I honestly know nothing about rear axles. And I want to get rid of the 4.10 and install 3.55, thanks for all the info, There are some shims in place, as far as the spacer goes, I dont know, I will take another look..

Thanks guys
 

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You have the correct carrier. All you need is the 3.55 gear set.

Steve
 

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Could he not have the 'thick' ring gear 4:10 set? Or is the thick one that fits a 3-series an aftermarket-only piece? The thin one fits a 4-series for only sure, unless used with a spacer.
 

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I have not seen a thick GM 4.10, but that doesn't mean there isn't one. If it is a thick GM gear I would like to see it.

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'69 RS/SS396 pro street
427/4spd/9"
Byars Performance
High Performance Drive Train Parts And Service
www.lubedealer.com/biggearhead
 

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There is a "thick" gear but GM didn't market it. His part number is correct for the standard 41 ring gear. I have a setup just like his on the shelf in the garage. What is most likely confusing him is that the ring gear spacer machining may be such that it looks like its part of the ring gear. GM, to the best of my knowledge, never made them and you had to go to your speed shop for one. The OD on mine is a little ratty so there is no problem making it out but if it had a course feed finish on it, after some years of use, it would look like part of the ring. Richmond makes a thick gear. Look in Jegs or Summit. The Jegs # for the thick one is 836-49-0304-1.

Steve
 

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Discussion Starter #16
Hey guys, I sent the pics, so check your email..

I took another good look, and I think there is a spacer in between, so its probably a 3-series, and there are about 3 shims each side. take a look at the pics.

Also another side issue, I have grooves on the side of my carrier, the same shape as the teeth on the ring gear..?? Dont think they belong there. Maybe the rearend blew-up once, and the gears cut into the side of the carrier???

Please take a look and tell me what you think.

Thanks 4 all the help.
 

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Yep.
You've got the spacer.
It also looks like somewhere down the line your crush sleeve gave it up. Perhaps that is when the 4.10's showed up. That happened to me in a long GMC 3/4 ton van I had for toting around scuba gear. Thank goodness it was in the snow cause the pinion got into banjo and it all stopped back there. Slid around a little. Crawled under, saw what happened, stuck it in reverse and it shot back out. Stayed there for the 3 blocks it needed.

good luck

Steve
 

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Yes, you have the spacer. The differential shims are not original either. Someone has built this rear end. The grooves in the case are from a earlier problem, maybe a pinion bearing went bad, real bad.

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'69 RS/SS396 pro street
427/4spd/9"
Byars Performance
High Performance Drive Train Parts And Service
www.lubedealer.com/biggearhead
 

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After looking at the pictures I realized that the finish on the OD of the spacer was exactly like mine. The spacer appears to be a slab cut off of a large hot rolled round, drilled, and ground. It seems like something the General would do that an aftermarket wouldn't. I can't help but wonder if the General didn't supply spacers back then. I know that when I needed them the parts guy sent me to the speed shop but that might have been because the spacers were a pain to get rather than being unavailable. I guess I have to split it open again and look for a part number.

Steve
 

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This is a after market spacer. If this rear end is supose to have a 4.10 in it, then someone probably broke the 4 series posi that was in it and replaced it with a 3 series posi and spacer. GM did not build this rear end this way.

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'69 RS/SS396 pro street
427/4spd/9"
Byars Performance
High Performance Drive Train Parts And Service
www.lubedealer.com/biggearhead
 
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