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

hdff · 10-21-2014, 09:42 AM

does anyone know what the most common rear end from the factory was on a c10 with a 402 big block. i am assuming either a 3.73 or a 4.11.

turp mcspray · 10-21-2014, 10:07 AM

It believe it was 3.07.

hounddogs! · 10-21-2014, 10:53 AM

1/2 T + BBC = 3.54 Dana 60 much of the time.

hdff · 10-21-2014, 11:07 AM

Quote:

Originally Posted by hounddogs!

1/2 T + BBC = 3.54 Dana 60 much of the time.

what i do know about mine is it doesn't have a dana by looking at the bolt pattern

turp mcspray · 10-21-2014, 11:40 AM

I think the big block 1/2 tons only used a dana, if it had a stick. Autos used the 12 bolt.

68Gold/white · 10-21-2014, 01:42 PM

My 68 396 (TH400) is a 12 bolt 3.07....

Mike C · 10-21-2014, 08:51 PM

I'm with the other guys. Most 1/2 ton big block trucks will be 3.07. Most 3/4 ton trucks will be 3.54 Dana 60.

The semi-float 60 with 6 lugs was pretty uncommon and I don't think is found after '69?

engineer_gregh · 10-21-2014, 09:09 PM

According to the GM Heritage doc the standard offering was 3.07 for the 402 engine. At least for the 1971 model. See page 18.

hdff · 10-21-2014, 09:44 PM

Quote:

Originally Posted by engineer_gregh

According to the GM Heritage doc the standard offering was 3.07 for the 402 engine. At least for the 1971 model. See page 18.

thanks for the info greg. I am just waiting for a week day off to take her to a rear end shop for repair and find out what is in there. I am considering going back with either a 3.73.or a 4.11 with a posi. hopefully a couple of more weeks and then a weekday off. here is the rear end and from what I have found this is not a dana rear end. I don't know why it is uploading upside down in my file it is not

da-burb · 10-21-2014, 10:47 PM

Quote:

Most 1/2 ton big block trucks will be 3.07. Most 3/4 ton trucks will be 3.54 Dana 60.

I second Mike C on the C10 vs C20 BBC rear gears.
hdff, You have a 12 bolt in your picture.

**special-K** · 10-22-2014, 09:00 AM

Big Block C/20 automatics got Dana 60/3.54s and C/10 automatic got 12-bolt/3.08s

engineer_gregh · 10-22-2014, 10:22 AM

Here is the link for the complete document. If you go with a 4.11 I believe you would have to change the complete rear housing. I've seen 3.73 gears that will fit into the 3 series carriers now. Maybe some of the more experienced guys can chime in once you know what you have currently.

https://www.gmheritagecenter.com/doc...olet-Truck.pdf

**69 MOD** · 10-22-2014, 11:09 AM

If you want to quick check it at home so you have a close idea of your ratio here's how:

Place a mark on the top of your tire, and a mark on your driveshaft (chalk/grease pen/marker)

Block your front tires so the truck can't roll, jack up the rear end.
Rotate the tire and watch the driveshaft, at 1 full revolution of the tire the mark on the driveshaft will have turned "X" amount of times.

This number will be your ratio
Example: 3 1/2 rotations of the driveshaft would most likely be 3.54 gears, just over 3 rotations = 3.07 etc.

Just a quick way to find the ratio without fully disassembling the rear end...

MOD

10-21-2014, 09:42 AM	#1
hdff Registered User Join Date: Apr 2007 Location: pasadena,TEXAS Posts: 880	rear end factory option does anyone know what the most common rear end from the factory was on a c10 with a 402 big block. i am assuming either a 3.73 or a 4.11. __________________ 1971 Cheyenne SWB 402BB, 700R4, 3.73 posi, PS, PB, A/C, Tilt, Tach "Wanda" Don't argue with idiots, People watching may not be able to tell the difference... There's someone in my head........But it's not me...... cheap tricks thread great info here!! http://67-72chevytrucks.com/vboard/s...d.php?t=489394

10-21-2014, 10:07 AM	#2
turp mcspray Registered User Join Date: May 2007 Location: Rapid City South Dakota Posts: 2,359	Re: rear end factory option It believe it was 3.07. __________________ Turp Mcspray New life for an old 2wd, farm blazer http://67-72chevytrucks.com/vboard/s...d.php?t=505987 My Blazer build http://67-72chevytrucks.com/vboard/s...d.php?t=342299

10-21-2014, 10:53 AM	#3
hounddogs! Restoring it $200 at a time... Join Date: Aug 2008 Location: NE Kansas Posts: 886	Re: rear end factory option 1/2 T + BBC = 3.54 Dana 60 much of the time. __________________ Charter member of the 'Put the dimmer switch back on the damn floor where it belongs' Society '68 5.3L-4 speed LWB C20; grandpa bought it for the farm in '71. Now LS 5.3, rather than 327. DD '09 Pilot Weekender '65 Skylark 300-4V-4 speed Wife's '07 Lexus ES350; 117 actuator motors and I can't see the engine. Son's '04 F250 SuperCab 6.0

10-21-2014, 11:40 AM	#5
turp mcspray Registered User Join Date: May 2007 Location: Rapid City South Dakota Posts: 2,359	Re: rear end factory option I think the big block 1/2 tons only used a dana, if it had a stick. Autos used the 12 bolt. __________________ Turp Mcspray New life for an old 2wd, farm blazer http://67-72chevytrucks.com/vboard/s...d.php?t=505987 My Blazer build http://67-72chevytrucks.com/vboard/s...d.php?t=342299

10-21-2014, 01:42 PM	#6
68Gold/white Registered User Join Date: Sep 2011 Location: Ark City, Kansas Posts: 3,327	Re: rear end factory option My 68 396 (TH400) is a 12 bolt 3.07....

10-21-2014, 08:51 PM	#7
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,715	Re: rear end factory option I'm with the other guys. Most 1/2 ton big block trucks will be 3.07. Most 3/4 ton trucks will be 3.54 Dana 60. The semi-float 60 with 6 lugs was pretty uncommon and I don't think is found after '69? __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

10-22-2014, 09:00 AM	#11
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,861	Re: rear end factory option Big Block C/20 automatics got Dana 60/3.54s and C/10 automatic got 12-bolt/3.08s __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

10-22-2014, 10:22 AM	#12
engineer_gregh Registered User Join Date: Feb 2012 Location: Smyrna TN Posts: 1,153	Re: rear end factory option Here is the link for the complete document. If you go with a 4.11 I believe you would have to change the complete rear housing. I've seen 3.73 gears that will fit into the 3 series carriers now. Maybe some of the more experienced guys can chime in once you know what you have currently. https://www.gmheritagecenter.com/doc...olet-Truck.pdf __________________ 1971 Longbed BB Cheyenne Super 1972 Longbed SB Cheyenne Super 1972 Longbed Highlander Custom Deluxe 1975 K5 4x4 full convertible Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=645165 Greg Smyrna TN

10-22-2014, 11:09 AM	#13
69 MOD Senior Member Join Date: May 2013 Location: Lino Lakes, MN Posts: 362	Re: rear end factory option If you want to quick check it at home so you have a close idea of your ratio here's how: Place a mark on the top of your tire, and a mark on your driveshaft (chalk/grease pen/marker) Block your front tires so the truck can't roll, jack up the rear end. Rotate the tire and watch the driveshaft, at 1 full revolution of the tire the mark on the driveshaft will have turned "X" amount of times. This number will be your ratio Example: 3 1/2 rotations of the driveshaft would most likely be 3.54 gears, just over 3 rotations = 3.07 etc. Just a quick way to find the ratio without fully disassembling the rear end... MOD __________________ Chad '71 GMC 2500 Custom Ol Blue '72 Custom Deluxe Highlander Stuffed Olive '73 Trans Am '13 Silverado 2500 Duramax Storm Trooper Last edited by 69 MOD; 10-22-2014 at 11:35 AM.



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