Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

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I have saved these from different places so they don't match each other. I saved them as image files and they are all different resolutions and sizes. They really need to be typed into a document file so the size and style of font matches on all of the charts. Unfortunately I don't type good enough to do that so we will try it this way. I just hope they are all readable with the image size restrictions for the board. I think I have them sized close to the maximum that the board allows. Disregard the C14 designation in the '67 chart, it should be C10.

In case someone is thinking Photobucket or some other photo hosting service, I won't do that for two reasons. One, I am not going to sign up for an account & Two, If the photobucket account is ever closed the thread will be worthless because their won't be any pictures of the charts in it, just empty boxes ...

Thanks.

LockDoc

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

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This is the last Chart. It looks like they are mostly readable. A couple of them may be a little blurry.

There is no guarantee of correctness or completeness (is that a word?) in any of these charts

Edit: I might as well add this chart to the thread too.

Rear Axle Ratios

Ratio 2.56:1 - Tooth Combination 41,16
Ratio 2.73:1 - Tooth Combination 41,15
Ratio 3.07:1 - Tooth Combination 43,14
Ratio 3.08:1 - Tooth Combination 40,13
Ratio 3.08:1 - Tooth Combination 37,12
Ratio 3.31:1 - Tooth Combination 43,13
Ratio 3.36:1 - Tooth Combination 37,11
Ratio 3.42:1 - Tooth Combination 41,12
Ratio 3.55:1 - Tooth Combination 39,11
Ratio 3.73:1 - Tooth Combination 41,11
Ratio 4.10:1 - Tooth Combination 41,10
Ratio 4.11:1 - Tooth Combination 37,9
Ratio 5.14:1 - Tooth Combination 36,7

The tooth combination numbers will be found stamped into the ring gear when you take the back cover off.

They may not all be for the trucks.

LockDoc

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Nice job LocDoc, thanks for posting those.

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

This is great! I'm thinking this is for Chevrolet with the 10,20,30 designates. And,I don't see any posi for K/20,only No-Spin. A Dana 60 would have the Power-lok. It shows a 4.11 for K/20,which is the Dana 60,

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Thanks LockDoc!

:metal:

I'm sure many people will be less confused. Now there is a place to direct people searching for that elusive code!

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

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No problem guys. It might be nice to have them all in one place. I added some info to my 2nd post also.

LockDoc

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

where can you find these codes on the axel?

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

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Usually on the passengers side axle tube. Just use the first 2 or 3 letters which ever it has.

LockDoc

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Thanks for posting those, Doc.

I'm not offended that the fonts and sizes don't match. Lends credibility to the documents, in my way of thinking.

k

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

I never knew of a 3.36:1 ratio in these trucks. Looks like it was just in Vans. That would be a sweet ratio to swap into a little C/10

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Thank you for posting. Great information.

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Good stuff.

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Yes, it is. Subscribed.

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

I climbed under the truck this afternoon and coudln't find the axle code on the tube. Could they have put it under the spring mount? I REALLY don't want to unbolt the springs to check it.

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Are you talking the front axle? dana 44? that axle stamp is just to the right of the front of the pumpkin towards the upper area..

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

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I don't think it would be under the mount. Sometimes they are stamped pretty light. There may be some that didn't get stamped. If that is the case you would have to pull the rear cover off, check the numbers on the ring gear and use the "Red" chart in post #2...

Example: If the numbers 41 : 11 were stamped into the edge of the ring gear it would be a 3.73 ring & pinion.

LockDoc

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

This is for the Eaton HO52 under the Longhorn.


Thanks Leon. It may not have been stamped or these old peepers just didn't catch them. I'll look again from different angles. It may also help to get my 5 year old under there. She sees EVERYTHING.

Thanks for your guys help on this subject. I truly appreciate it.

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

No problem. Be sure and take a strong light and some coarse sandpaper under with you...

Funny how those kids see it all....

LockDoc

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Look on top of the pumpkin passenger side of the pumpkin. I didn't think the Eaton had a stamp on the axle, i didn't see one on mine.

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

OK I'll look there too. I did see some stuff stamped there.

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Okay, here's a total noob question, please don't flame me too badly :)...

For 1967 what's a C14 and why isn't there a C10 in the chart? Quick google on 1967 and C14 yielded nonsense. Is that a misprint for C10?

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

well since i dont see it yet. I can probably OCR these are convert them to text. Ill fiddle with it today.

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Well my OCR software is kind of crappy but it wont take to much to clean this up. You guys prefer csv, xls or just a text file. the coloms are never going to line up correctly in the forum so it should be a download of some kind.

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

I don't see a c14 listed for '67 in any of my literature so it is probably a misprint...

LockDoc

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

For 67 is c14 3.73 positraction the equivalent to a 67 c10 with 3.73 posi?

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Ok, according to this, 1967 c20 duallys do exist?

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Here's another resource for differential (and engine, and VIN) codes.

http://www.gmcpauls.com/67-72_chevy.htm

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

:chevy: Subscribed, good info here :metal::metal::metal:

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Thanks for posting this Leon. I need this info from time to time and always had to look for it. Is there a 1971 page like the 1972 chart in post #2? I just need the 5 lug stuff....

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

The '71 chart is at the bottom of post #1. Is that what you need?

LockDoc

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

"The '71 chart is at the bottom of post #1. Is that what you need?"

Yes, that's it and I just missed it. Thanks!

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Is there any other places to look for the codes? I have a 69 C10, on the passenger side axle tube: "R V 0630 W2", and under that an "E", I do not see any code like it, does anyone know what ratio it is? Thanks

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Did you look in the location pictured in post #19?

LockDoc

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

I will try there, from reading the posts I thought you guys were talking about a "K" series Dana. Thanks!

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

so judging by what you've posted for a picture the TDE would stand for 3.07:1 gears ina C10? What would the 11 and 13 stand for?

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

That would be correct. I think that may be a date code ie: 11th month, 13th day but I don't know for sure.

LockDoc

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Dave ;

Never fear any flaming here ! .

The good folks here collectively know _everything_ and are always willing to share , no question is foolish no matter how mundane you think it is .

O.K. ? .

Seriously , i worked on these trucks when new , later i was a Dealer Mechanic and I have learned more here than all those years of hands on working so ASK AWAY ! :metal: .

:chevy:

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

thank you!!!

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

No problem, glad folks are getting some use out of the info....

LockDoc

Re: Rear Axle Ratio Charts For 1967 - 1972 GM Trucks
 

Great post! lots of good info here. the trouble I'm having is I cannot find my code! it reads as follows and I am not mistaken. TAY W175 2. will post pics if it becomes necessary but theres a good chance I'm missing it somewhere amongst all the darn codes. Any ideas?

thanks in advance,
chefk85