3:07 and 3:08 what is the diff???? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

67chevemall · 04-13-2005, 04:29 PM

What year was stock in 67? 08's or 07's?
What came with what trucks c/10 c/20
Do they use the same carrier?
Any links or tips would be great!
Some people are asking for 3:07's
While I thought it was 3:08's for 67-72??

Blazer1970 · 04-13-2005, 05:18 PM

For all intents and purposes they are the same thing.

skokie · 04-13-2005, 05:20 PM

As crazy as this sounds I was told that 3.07 went into trucks and 3.08s went into cars.

Longhorn Man · 04-13-2005, 06:08 PM

67 - 72 C/10 could be had with a 3.07...C/20 had nothing even close.
While in all reality, they are pretty mucvh the same...but the trucks never had 3.08 stock...not 67 - 72 anyways.

XXL · 04-13-2005, 06:13 PM

.01?

Brainchild · 04-13-2005, 07:05 PM

Quote:

Originally Posted by skokie

As crazy as this sounds I was told that 3.07 went into trucks and 3.08s went into cars.

I think that is right Skokie.I pulled many Nova/Chevelle/impala rearends apart and they would have 3.08 gears.

Rod · 04-13-2005, 07:42 PM

Yeah its a car ratio being 3.08 to truck being 3.07. just a rounding off of the division.....you also get confusion with the dana truck compared to eaton/ corp truck ratio.....rounding them off you get dana being 4.56 and corp/eaton being 4.57.

dana having gear counts of 41/9= 4.55555 or 4.56

corp having gears of 32/7 = 4.571428 or 4.57

71-longbed · 04-13-2005, 07:47 PM

i always refered to them as 3.08's until i counted the ring and pinion on my old gears and divided it and got 3.07 .....either way the general point gets across .... highway gears

67chevemall · 04-13-2005, 08:33 PM

Thanks for the posts. That is great.
Do they use the same carrier then?
Or is it safer to get the gears and carrier from the same rear end?

70 shorty · 04-13-2005, 09:09 PM

Yeah, my Z28 has 3.08 gears from the factory. Not for long though, as soon as I can get the 3.42 posi I have detailed it's going in it's place.

*screamin_c102* · 04-13-2005, 09:18 PM

I used to have a '61 Ferd 3/4 ton 4x4 it had a Ford rearend w/4.10s and a Dana 44 with 4.09s. Never had a problem with gear bind on asphalt or hardpack. Built 460 and a C-6 boy she'd put away a few gallons of fuel...

CHEVIBUBBA · 04-13-2005, 11:09 PM

there are only two different ring & pinion combo's in gm rears that come anywhere close to 3.08:1 ratio;37-12 & 40-13.
the 37-12 works out to 3.08333333:1
the 40-13 works out to 3.07692307:1
neither of which can round down to 3.07.
the 3.07 does not exist in gm products.
IT'S A 3.08!!!!!

Scrubby · 04-13-2005, 11:49 PM

Quote:

Originally Posted by CHEVIBUBBA

the 3.07 does not exist in gm products.
IT'S A 3.08!!!!!

Umm. Why does this brochure from 1972 say the ratio is 3.07:1 then?

http://www.tocmp.com/brochures/GMTru...ion-12_jpg.htm

CHEVIBUBBA · 04-13-2005, 11:58 PM

Quote:

Originally Posted by Scrubby

Umm. Why does this brochure from 1972 say the ratio is 3.07:1 then?

http://www.tocmp.com/brochures/GMTru...ion-12_jpg.htm

ok. i'll play your silly game.why does it say the ratio is 3.07:1?
uuuummmmm, it's a sales brochure. & some survey done by gm told the sales team that 3.07:1 was a popular ratio?
this ain't fuzzy math.
do it on YOUR calculator.

Longhorn Man · 04-14-2005, 12:07 AM

OK..you ask...and here is an asnwer.
Car 12 bolts and truck 12 bolts are not the same thing.
So, make life easy, and only list the .xx instead of rounding, or listing .xxx or .xxxx.
Now then, since we are only going to the hundredths position, and one is .08, and one is .07, we can easily know what is what. If you walked into a shop and said you needed a 3,07 for your 12 bolt, the GM tech would know right off the bat that we were dealin with a truck 12 bolt...and not a car 12 bolt.
There is no rounding... no BS...just the simple fact that one is a 3.07, and the other is a 3.08.
That's it, plain and simple, 3.07 is truck, 3.08 is car.
Too hard to grasp?

71-longbed · 04-14-2005, 12:27 AM

:d

CHEVIBUBBA · 04-14-2005, 12:40 AM

'cept only the 40-13 tooth r&p are available for the truck & car 12 bolts.
btw the ring gears are the same.only the pinions are different.
the 37-12 is only available in some early ten bolts.
that means the 12 bolt car ratio=3.07692307:1
& the 12 bolt truck ratio=3.07692307:1
or 3.08:1
or 308.

*screamin_c102* · 04-14-2005, 01:23 AM

**pjmoreland** · 04-14-2005, 02:10 AM

I had a 12-bolt posi 3.07 in my truck a couple of years ago. I also bought a 3.07 set about 3 months ago out of a 1971 Chevy truck with a 12-bolt rear end. It was also a posi unit. They were both 14-43 gears.

43/14=3.07142857

Rod · 04-14-2005, 08:37 AM

The trucks are 43/14 =3.07142857 like pj does his math

Not the first time I've seen foot in mouth disease.
40/13..thats 3.08 which is common in a 1968 oldsmobile not a truck!

As for 4x4 front.... they are typically 4.55 front or 4.09 front in 3/4 ton 4x4 of this vintage depending what rear ratio you had.

71cadc10 · 04-14-2005, 12:17 PM

second that, my 12 bolt truck rear from 71 C10 had 43/14. 3.07 just counted last night

My guess is that 40/13 were car gears, and maybe the 73up truck gear sets

I do agree with Chevibubba though, the only new gearsets I seem to find are 40/13 whether truck or car now.

ehjorten · 04-14-2005, 03:31 PM

Okay...so all other things being the same a 3.07:1 at 60 MPH is 60.6 MPH with a 3.08:1. That is the difference!

67chevemall · 04-14-2005, 03:45 PM

??

Crazy stuff man!

**pjmoreland** · 04-14-2005, 05:16 PM

Actually it would be 60.2 with a 3.08.

(3.08/3.07) x 60 = 60.195

ehjorten · 04-14-2005, 05:46 PM

Yeah...your right...I was just focusing on the 0.01 numerical difference.

Well...there you have it, 0.2 MPH difference! Better go with the 3.08 ratio so you will accelerate quicker!

Oh...incidentally you have to go about 315 MPH until it makes a 1 MPH difference.

04-13-2005, 04:29 PM	#1
67chevemall Registered User Join Date: Apr 2003 Location: NB Posts: 3,367	3:07 and 3:08 what is the diff???? What year was stock in 67? 08's or 07's? What came with what trucks c/10 c/20 Do they use the same carrier? Any links or tips would be great! Some people are asking for 3:07's While I thought it was 3:08's for 67-72?? __________________ 1968 Chevy C10 307 3ott fleetside 1967 Chevy C/10 V8, 3spd, fleetside lwb.Sold 1967 Chev C/10 step, 383, M21. SOLD

04-13-2005, 05:18 PM	#2
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,510	For all intents and purposes they are the same thing. __________________ Tim

04-13-2005, 05:20 PM	#3
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,342	As crazy as this sounds I was told that 3.07 went into trucks and 3.08s went into cars. __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

04-13-2005, 06:13 PM	#5
XXL Señor Member Join Date: May 2002 Location: Edge of the world Posts: 5,367	.01? __________________ Craigslist \| ebay \| Engrishtees \| www.myattitudesucks.com \| Follow me on Twitter

04-13-2005, 07:42 PM	#7
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	Yeah its a car ratio being 3.08 to truck being 3.07. just a rounding off of the division.....you also get confusion with the dana truck compared to eaton/ corp truck ratio.....rounding them off you get dana being 4.56 and corp/eaton being 4.57. dana having gear counts of 41/9= 4.55555 or 4.56 corp having gears of 32/7 = 4.571428 or 4.57 __________________ Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife.

04-13-2005, 06:08 PM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	67 - 72 C/10 could be had with a 3.07...C/20 had nothing even close. While in all reality, they are pretty mucvh the same...but the trucks never had 3.08 stock...not 67 - 72 anyways.

04-13-2005, 07:47 PM	#8
71-longbed Its Magically Delicious Join Date: Jan 2003 Location: oregon Posts: 2,398	i always refered to them as 3.08's until i counted the ring and pinion on my old gears and divided it and got 3.07 .....either way the general point gets across .... highway gears __________________ 71 C10 LWB 350sbc -TH350 12 bolt 3.42 Posi Of all my favorite things to do, The utmost is to have a brew. My love grows for my foamy friend, with each thirst-quenching elbow bend. Beer so frosty, smooth, and cold it's paradise pure liquid gold. Yes beer means many things to me that's all for now cus I gotta pee.

04-13-2005, 08:33 PM	#9
67chevemall Registered User Join Date: Apr 2003 Location: NB Posts: 3,367	Thanks for the posts. That is great. Do they use the same carrier then? Or is it safer to get the gears and carrier from the same rear end? __________________ 1968 Chevy C10 307 3ott fleetside 1967 Chevy C/10 V8, 3spd, fleetside lwb.Sold 1967 Chev C/10 step, 383, M21. SOLD

04-13-2005, 09:09 PM	#10
70 shorty Where's my beer? Join Date: Oct 2004 Location: Glen Allen, VA Posts: 1,772	Yeah, my Z28 has 3.08 gears from the factory. Not for long though, as soon as I can get the 3.42 posi I have detailed it's going in it's place. __________________ 70 C10, shortstep, .30 over 250,Hurst shifted 3 spd parts hauler. Holley 390, Clifford Intake, Header, ported cylinder head, unknown bigger cam. 79 Corvette L82, 4 spd, black, red interior, headers, flowmasters, and unkown bigger cam. '03 Grand Cherokee Laredo, 4.0 4x4 daily driver. 165K miles, and runs great '08 Tahoe LTZ 4x4 155K

04-13-2005, 09:18 PM	#11
screamin_c102 Account Suspended Join Date: Feb 2005 Location: Yoncalla Oregon Posts: 775	I used to have a '61 Ferd 3/4 ton 4x4 it had a Ford rearend w/4.10s and a Dana 44 with 4.09s. Never had a problem with gear bind on asphalt or hardpack. Built 460 and a C-6 boy she'd put away a few gallons of fuel...

04-13-2005, 11:09 PM	#12
CHEVIBUBBA got boost? Join Date: Mar 2005 Posts: 123	there are only two different ring & pinion combo's in gm rears that come anywhere close to 3.08:1 ratio;37-12 & 40-13. the 37-12 works out to 3.08333333:1 the 40-13 works out to 3.07692307:1 neither of which can round down to 3.07. the 3.07 does not exist in gm products. IT'S A 3.08!!!!! __________________ '70 chevy lwb w/'67 hood. 357 s.b.c. built, 4l60 w/vigilante lockup high stall converter, edelbrock pro-flo,brodix heads,comp cams rollerized w/ belt drive, one piece d-shaft, yada, yada, yada..... '82 honda v45 sabre"the black"

04-14-2005, 12:07 AM	#15
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	OK..you ask...and here is an asnwer. Car 12 bolts and truck 12 bolts are not the same thing. So, make life easy, and only list the .xx instead of rounding, or listing .xxx or .xxxx. Now then, since we are only going to the hundredths position, and one is .08, and one is .07, we can easily know what is what. If you walked into a shop and said you needed a 3,07 for your 12 bolt, the GM tech would know right off the bat that we were dealin with a truck 12 bolt...and not a car 12 bolt. There is no rounding... no BS...just the simple fact that one is a 3.07, and the other is a 3.08. That's it, plain and simple, 3.07 is truck, 3.08 is car. Too hard to grasp?

04-14-2005, 12:27 AM	#16
71-longbed Its Magically Delicious Join Date: Jan 2003 Location: oregon Posts: 2,398	:d __________________ 71 C10 LWB 350sbc -TH350 12 bolt 3.42 Posi Of all my favorite things to do, The utmost is to have a brew. My love grows for my foamy friend, with each thirst-quenching elbow bend. Beer so frosty, smooth, and cold it's paradise pure liquid gold. Yes beer means many things to me that's all for now cus I gotta pee.

04-14-2005, 12:40 AM	#17
CHEVIBUBBA got boost? Join Date: Mar 2005 Posts: 123	'cept only the 40-13 tooth r&p are available for the truck & car 12 bolts. btw the ring gears are the same.only the pinions are different. the 37-12 is only available in some early ten bolts. that means the 12 bolt car ratio=3.07692307:1 & the 12 bolt truck ratio=3.07692307:1 or 3.08:1 or 308. __________________ '70 chevy lwb w/'67 hood. 357 s.b.c. built, 4l60 w/vigilante lockup high stall converter, edelbrock pro-flo,brodix heads,comp cams rollerized w/ belt drive, one piece d-shaft, yada, yada, yada..... '82 honda v45 sabre"the black"

04-14-2005, 01:23 AM	#18
screamin_c102 Account Suspended Join Date: Feb 2005 Location: Yoncalla Oregon Posts: 775



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04-14-2005, 02:10 AM	#19
pjmoreland Senior Member Join Date: Jan 2005 Location: CA Posts: 5,786	I had a 12-bolt posi 3.07 in my truck a couple of years ago. I also bought a 3.07 set about 3 months ago out of a 1971 Chevy truck with a 12-bolt rear end. It was also a posi unit. They were both 14-43 gears. 43/14=3.07142857

04-14-2005, 08:37 AM	#20
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	The trucks are 43/14 =3.07142857 like pj does his math Not the first time I've seen foot in mouth disease. 40/13..thats 3.08 which is common in a 1968 oldsmobile not a truck! As for 4x4 front.... they are typically 4.55 front or 4.09 front in 3/4 ton 4x4 of this vintage depending what rear ratio you had. __________________ Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife.

04-14-2005, 12:17 PM	#21
71cadc10 Registered User Join Date: Apr 2004 Location: Boiling Springs, PA Posts: 435	second that, my 12 bolt truck rear from 71 C10 had 43/14. 3.07 just counted last night My guess is that 40/13 were car gears, and maybe the 73up truck gear sets I do agree with Chevibubba though, the only new gearsets I seem to find are 40/13 whether truck or car now. __________________ 71 C10 long bed, 2003 6.0L, 06GTO E40, T56, 12bolt 4.10 rear Last edited by 71cadc10; 04-14-2005 at 12:19 PM. Reason: add info

04-14-2005, 03:31 PM	#22
ehjorten Registered User Join Date: Jan 2001 Location: Kirkland, WA, U.S.A. Posts: 32	Okay...so all other things being the same a 3.07:1 at 60 MPH is 60.6 MPH with a 3.08:1. That is the difference! __________________ '68 Chevy Stepside in Frame-up Restoration process. 292 CID Clifford Performance Modified T56 6-speed Tranny Slammed, Custom IFS and IRS Money?...Too Much!

04-14-2005, 03:45 PM	#23
67chevemall Registered User Join Date: Apr 2003 Location: NB Posts: 3,367	?? Crazy stuff man!

04-14-2005, 05:16 PM	#24
pjmoreland Senior Member Join Date: Jan 2005 Location: CA Posts: 5,786	Actually it would be 60.2 with a 3.08. (3.08/3.07) x 60 = 60.195

04-14-2005, 05:46 PM	#25
ehjorten Registered User Join Date: Jan 2001 Location: Kirkland, WA, U.S.A. Posts: 32	Yeah...your right...I was just focusing on the 0.01 numerical difference. Well...there you have it, 0.2 MPH difference! Better go with the 3.08 ratio so you will accelerate quicker! Oh...incidentally you have to go about 315 MPH until it makes a 1 MPH difference. __________________ '68 Chevy Stepside in Frame-up Restoration process. 292 CID Clifford Performance Modified T56 6-speed Tranny Slammed, Custom IFS and IRS Money?...Too Much!

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