Rear ratio question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**ScottH** · 01-12-2004, 11:13 AM

Can anyone tell me what the ratio would be for a 72 C10 posi rear (with leaf springs if that makes a difference)? The option sheet lists the posi, but no ratio. I was under the impression that a 3:73 would be listed separately as an option (was in another 72 I had, but no posi in that one), but not sure.

Any info is appreciated. Thanks guys.

**ScottH** · 01-12-2004, 06:39 PM

ttt

Tx Firefighter · 01-12-2004, 06:52 PM

MOST 350 trucks had 3.08

Bill72BB · 01-12-2004, 07:10 PM

What engine and trans?

**ScottH** · 01-12-2004, 11:25 PM

Bill72BB, I was told it was originally a 350 4-speed.

Thanks for the info.

Scott

**Stocker** · 01-12-2004, 11:35 PM

Why not spin the tires and count the driveshaft revolutions - or pull the cover and count the teeth?

**ScottH** · 01-12-2004, 11:46 PM

Stocker, I haven't picked the truck up yet (72 parts truck). I want to get the truck mainly to use the posi in a 68 I have, but from what I understand I need to make sure the ratios are close in order to use the posi carrier in the 68 rear. The truck probably isn't worth getting if I can't use the rear.

thanks.

Scott

Bill72BB · 01-13-2004, 12:56 AM

350 /4 speed 3.07 stock, 3.73or 4.11 optional

padreisla · 01-13-2004, 01:26 AM

Ok, since you all are answering rear end questions. My 67 3/4 lwb originally had 6 cyl in it with I believe a 3 speed, this has all been replace with a 454 and a 400 TH. I have been told that the rear end is either a corporate or rockwell. How can I identify it and do any of you have any idea of what the ratio might be.

1969 GMC · 01-13-2004, 02:45 AM

your rearend is the eaton/corporate ho52. it should have 4.10 or 4.56 gears, i forget which was standard and which was optional though.

**ScottH** · 01-13-2004, 11:30 AM

Thanks to all for all the great info!

padreisla · 01-13-2004, 11:41 PM

Hey 1969 GMC, were you referring to the rear end in my truck. If so I would really like to lower the gears, do you know where I might be able to get lower gears without breaking the bank? I was thinking about going to something around a 3:5?.

Longhorn Man · 01-14-2004, 12:06 AM

You'll be hard pressed to do it in reality...at least on a buget anyways.

01-12-2004, 11:13 AM	#1
ScottH Senior Member Join Date: Sep 2002 Location: Hampstead, NC Posts: 8,190	Rear ratio question Can anyone tell me what the ratio would be for a 72 C10 posi rear (with leaf springs if that makes a difference)? The option sheet lists the posi, but no ratio. I was under the impression that a 3:73 would be listed separately as an option (was in another 72 I had, but no posi in that one), but not sure. Any info is appreciated. Thanks guys.

01-12-2004, 06:52 PM	#3
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	MOST 350 trucks had 3.08 __________________ I'm on the Instagram- @Gearhead_Kevin

01-12-2004, 07:10 PM	#4
Bill72BB Thats the Hillbilly way Join Date: Jul 2001 Location: Torrance,Ca Posts: 5,979	What engine and trans? __________________ BILL Torrance Calif 90504 Member DUF Club Member Old Farts Club 72 3/4ton Custom Camper BB402/400 trans Dynomax Cerama-coat headers , Hei distributor ,Edelbrock 1411 air,ps,pb,leafsprings ,98 chevy 60/40 seat,S10 shoulder belts tilt,3.54 Dana 60 rear. 16" Eagle wheels with LT265/75 16 tires,Gaylord Lid,H4 headlights with 100W relay conversion. " If I knew I was going to live this long I would have taken better care of myself " Marriage changes passion...suddenly you're in bed with a relative. A GUY'S PRAYER.... Lord, I pray for a nympho with huge boobs who owns a liquor store and likes to fish and hunt and has a Harley .Amen ,

01-12-2004, 11:35 PM	#6
Stocker 20' Daredevil (Ret) Join Date: May 2003 Location: Jefferson State Posts: 13,731	Why not spin the tires and count the driveshaft revolutions - or pull the cover and count the teeth? __________________ - Mike - 1972 K20 LWB 350/350/205 RIP El Jay

01-13-2004, 12:56 AM	#8
Bill72BB Thats the Hillbilly way Join Date: Jul 2001 Location: Torrance,Ca Posts: 5,979	350 /4 speed 3.07 stock, 3.73or 4.11 optional __________________ BILL Torrance Calif 90504 Member DUF Club Member Old Farts Club 72 3/4ton Custom Camper BB402/400 trans Dynomax Cerama-coat headers , Hei distributor ,Edelbrock 1411 air,ps,pb,leafsprings ,98 chevy 60/40 seat,S10 shoulder belts tilt,3.54 Dana 60 rear. 16" Eagle wheels with LT265/75 16 tires,Gaylord Lid,H4 headlights with 100W relay conversion. " If I knew I was going to live this long I would have taken better care of myself " Marriage changes passion...suddenly you're in bed with a relative. A GUY'S PRAYER.... Lord, I pray for a nympho with huge boobs who owns a liquor store and likes to fish and hunt and has a Harley .Amen ,

01-12-2004, 06:39 PM	#2
ScottH Senior Member Join Date: Sep 2002 Location: Hampstead, NC Posts: 8,190	ttt

01-12-2004, 11:25 PM	#5
ScottH Senior Member Join Date: Sep 2002 Location: Hampstead, NC Posts: 8,190	Bill72BB, I was told it was originally a 350 4-speed. Thanks for the info. Scott

01-12-2004, 11:46 PM	#7
ScottH Senior Member Join Date: Sep 2002 Location: Hampstead, NC Posts: 8,190	Stocker, I haven't picked the truck up yet (72 parts truck). I want to get the truck mainly to use the posi in a 68 I have, but from what I understand I need to make sure the ratios are close in order to use the posi carrier in the 68 rear. The truck probably isn't worth getting if I can't use the rear. thanks. Scott

01-13-2004, 01:26 AM	#9
padreisla Registered User Join Date: Jan 2003 Location: Tampa, Florida Posts: 141	Gear Ratio Ok, since you all are answering rear end questions. My 67 3/4 lwb originally had 6 cyl in it with I believe a 3 speed, this has all been replace with a 454 and a 400 TH. I have been told that the rear end is either a corporate or rockwell. How can I identify it and do any of you have any idea of what the ratio might be. __________________ 67 C20 LWB 454 BB THD 400 97 Jeep Wrangler 4cyl 5sp Last edited by padreisla; 01-13-2004 at 01:41 AM.

01-13-2004, 02:45 AM	#10
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	your rearend is the eaton/corporate ho52. it should have 4.10 or 4.56 gears, i forget which was standard and which was optional though. __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650

01-13-2004, 11:30 AM	#11
ScottH Senior Member Join Date: Sep 2002 Location: Hampstead, NC Posts: 8,190	Thanks to all for all the great info!

01-13-2004, 11:41 PM	#12
padreisla Registered User Join Date: Jan 2003 Location: Tampa, Florida Posts: 141	Rear End Hey 1969 GMC, were you referring to the rear end in my truck. If so I would really like to lower the gears, do you know where I might be able to get lower gears without breaking the bank? I was thinking about going to something around a 3:5?. __________________ 67 C20 LWB 454 BB THD 400 97 Jeep Wrangler 4cyl 5sp

01-14-2004, 12:06 AM	#13
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	You'll be hard pressed to do it in reality...at least on a buget anyways.



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