Well, surprise, surprise, SURPRISE! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

toddtheodd · 09-06-2004, 05:32 AM

So I went to pick up the rear end from MACKL that I purchased today as one happy individual. When I called him for directions I found out that the rear end was a 12 bolt.

Well.
When I got over there to pick it up I noticed something for the first time. My truck has a 12 bolt as well.

I've never really looked under my baby before and always just assumed that it was a 10 bolt.

So tell me this guys. What is a 3.08 non-posi 12 bolt coil spring rear end worth? Because after I get the 3.73's in mine I won't need the 3.08's anymore.

Also. How much does a posi run for a 12 bolt?

Todd

Tx Firefighter · 09-06-2004, 06:40 AM

No 10 bolts under these trucks. Even the lowly six cylinder trucks, like mine, came with 12 bolts.

bobs409 · 09-06-2004, 07:00 AM

The six cylinder trucks came with the 12 bolt 3.73 gears standard from what I've learned. My stepside has it.

Nothing all that special about these 12 bolts unlike finding one in a car. Two different animals.

dennis111 · 09-06-2004, 07:23 AM

Quote:

Originally Posted by Tx Firefighter

No 10 bolts under these trucks. Even the lowly six cylinder trucks, like mine, came with 12 bolts.

Not sure if I totally agree with this. I bought my 68' GMC (then 307ci, 3speed, 60,000miles) in 74' and it had a 10 bolt with a 3:42 ratio. Has since been updated with a 12 bolt.

Anyways, just an observation. . . . .

Longhorn Man · 09-06-2004, 07:51 AM

That rear had to have been swapped in. There was no 3.42 gears in these tricks either.

68C15 · 09-06-2004, 08:24 AM

my '68 GMC came with a 250, NP435?, & dana 44 with 3.54:1 on leaf springs.
I wish I had kept that.

da-burb · 09-06-2004, 08:32 AM

67-68 GMC's were available with Dana 44's. I also have a 68 burb with a Dana 44 and a posi 3.54 in back.

frogsmakr · 09-06-2004, 09:06 AM

i think that GMCs had DANAs.

Longhorn Man · 09-06-2004, 05:18 PM

A dana could be had in chevy or GMC trucks, but the base model rear was a 12 bolt

Robert1970C20rstbukt · 09-06-2004, 06:13 PM

Mine has a 10 bolt with optional 4:11's.

1969 GMC · 09-06-2004, 06:50 PM

some early GMC 1/2 tons (usually '68 BB models) had dana 60 semifloater rearends, and then there was also the dana 44 rear, which I can't recall ever hearing of under a chevy.

robert1970c20rstbukt, your truck is a 3/4 ton and has an Eaton rearend. 4.11 should be the standard ratio for that axle w/ 350.

Robert1970C20rstbukt · 09-06-2004, 09:48 PM

OK, thanks for the info. I thought they were optional, but I was thinking about 1/2 tons.

dennis111 · 09-07-2004, 07:07 AM

Quote:

Originally Posted by Tx Firefighter

No 10 bolts under these trucks. Even the lowly six cylinder trucks, like mine, came with 12 bolts.

Quote:

That rear had to have been swapped in. There was no 3.42 gears in these tricks either.

Even after 30 years of ownership, one can still learn something about their truck. Thanks guys!

09-06-2004, 05:32 AM	#1
toddtheodd The oddest Todd around Join Date: May 2004 Location: Miami, Florida Posts: 1,418	Well, surprise, surprise, SURPRISE! So I went to pick up the rear end from MACKL that I purchased today as one happy individual. When I called him for directions I found out that the rear end was a 12 bolt. Well. When I got over there to pick it up I noticed something for the first time. My truck has a 12 bolt as well. I've never really looked under my baby before and always just assumed that it was a 10 bolt. So tell me this guys. What is a 3.08 non-posi 12 bolt coil spring rear end worth? Because after I get the 3.73's in mine I won't need the 3.08's anymore. Also. How much does a posi run for a 12 bolt? Todd

09-06-2004, 06:40 AM	#2
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	No 10 bolts under these trucks. Even the lowly six cylinder trucks, like mine, came with 12 bolts. __________________ I'm on the Instagram- @Gearhead_Kevin

09-06-2004, 07:00 AM	#3
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	The six cylinder trucks came with the 12 bolt 3.73 gears standard from what I've learned. My stepside has it. Nothing all that special about these 12 bolts unlike finding one in a car. Two different animals. __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

09-06-2004, 08:24 AM	#6
68C15 blood type; Retumbo Join Date: Jan 2004 Location: next to my reloading bench Posts: 10,269	my '68 GMC came with a 250, NP435?, & dana 44 with 3.54:1 on leaf springs. I wish I had kept that. __________________ Man rule #77...if you own a 67 stepside with a caddy 472 you will never be in danger of loosing you man card

09-06-2004, 08:32 AM	#7
da-burb "Ochre Ogre" Join Date: Apr 2000 Location: Springfield, MN Posts: 3,558	67-68 GMC's were available with Dana 44's. I also have a 68 burb with a Dana 44 and a posi 3.54 in back. __________________ Bowtie Truck Stop Inc. Mid-West GM Truck Restoration Parts Supplier Your Key Parts, Auto Metal Direct, Dynacorn, and Goodmark dealer. like us @ www.facebook.com/BowtieTruckStop 1971 C-10 Suburban (Ochre) 1971 K-10 Suburban (Ochre) 1972 C-10 Suburban (Ochre) 1972 K-20 Suburban (Yellow- that just aint right!) Springfield, Minnesota 56087

09-06-2004, 07:51 AM	#5
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	That rear had to have been swapped in. There was no 3.42 gears in these tricks either.

09-06-2004, 09:06 AM	#8
frogsmakr Registered User Join Date: Feb 2000 Location: Sherwood AR Posts: 553	i think that GMCs had DANAs.

09-06-2004, 05:18 PM	#9
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	A dana could be had in chevy or GMC trucks, but the base model rear was a 12 bolt

09-06-2004, 06:13 PM	#10
Robert1970C20rstbukt Registered User Join Date: Jun 2004 Location: Beeville, Texas Posts: 1,943	Mine has a 10 bolt with optional 4:11's. __________________ RJD 1984 Chevrolet C30 welding truck 454/SM465 1977 GMC C15 pickup 350/TH350 1970 Chevrolet C20 pickup 350/TH400 1970 Chevrolet K20 Suburban 454/TH350 1969 GMC 8500 478M V6/5 spd winch truck

09-06-2004, 06:50 PM	#11
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	some early GMC 1/2 tons (usually '68 BB models) had dana 60 semifloater rearends, and then there was also the dana 44 rear, which I can't recall ever hearing of under a chevy. robert1970c20rstbukt, your truck is a 3/4 ton and has an Eaton rearend. 4.11 should be the standard ratio for that axle w/ 350. __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650

09-06-2004, 09:48 PM	#12
Robert1970C20rstbukt Registered User Join Date: Jun 2004 Location: Beeville, Texas Posts: 1,943	OK, thanks for the info. I thought they were optional, but I was thinking about 1/2 tons. __________________ RJD 1984 Chevrolet C30 welding truck 454/SM465 1977 GMC C15 pickup 350/TH350 1970 Chevrolet C20 pickup 350/TH400 1970 Chevrolet K20 Suburban 454/TH350 1969 GMC 8500 478M V6/5 spd winch truck

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