Question on rear axles... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jorgensensc · 03-21-2007, 09:13 PM

The truck I just got from a fellow board member (70 rs/ss) has front crossmember conversion off a 73-87 truck.. so 5 lug. The rear is a 6 lug off a '68 I think. (truck is a '68, but the rear axle isn't original, had 3.08s, he changed to 3.73s)
First qustion. What is the length from flange to flange on the pre 71 rear, and what is the length on the 71 and 72s? I would like to measure to make sure I know what rear I have. Did 71s and 72s have 6 lug coil spring in the 3/4 tons?

Second Question. Can I get the original axles redrilled for 5 lug? Or should I just spend the money on new axles.If so who has good prices? Money is kinda tight, and 70 rs/ss is going to send me some rallyes so he can get his tires and rims back that are on the truck now. They go to a couple of other projects he has, he just wanted to make sure that I had good tires for the drive home (what a guy!)

I will get pics as soon as I can! I know y'all want to see. I can say that the 1400 mile trip went off without a hitch. And I got about 14 mpg going 75-85 the whole way. Damn 2 barrels are cool!!
Thanks guys!
Shawn

Tx Firefighter · 03-21-2007, 09:33 PM

71-72 were all 5 lug on 1/2 ton and 8 lug on 3/4 tons.

If you have a 6 lug coil rear in it now, it's a 70 or earlier rear 1/2 ton.

You can either get a 71-72 rear, order special conversion axles (ECE has em) or convert a 73-87 rear to work. I prefer the 73-87 rear myself. You have to weld new saddles on it and use a super track bar, but that's all easy.

jorgensensc · 03-21-2007, 09:56 PM

THanks for the reply Kevin. So redrilling the originals is out of the question?

neonlarry · 03-21-2007, 10:09 PM

Rear Axle Measurements
MEASURED ACROSS WHEEL MOUNTING SURFACE
60-61" 64-69 1/2 ton 2wd Chevy/ Some GMC 6 lug rear end 12 bolt Coil spring set up
62" 70 2wd 6 lug rear end 12 bolt
71- Newer 2wd trucks use a 5 on 5 lug pattern
You can have yours redrilled, IIRC you will have to have at least one hole welded to do this.

Robznob11 · 03-21-2007, 10:11 PM

got mine from moser for 280.00 shipped and they are non tapered 40% stronger than origanals, im not positive but i think that 70 1/2 trucks had 6 lugs but were the wider rear like in the 71-72 you might ask around...

03-21-2007, 09:13 PM	#1
jorgensensc Registered User Join Date: Jul 2003 Location: Cypress, Tx Posts: 4,005	Question on rear axles... The truck I just got from a fellow board member (70 rs/ss) has front crossmember conversion off a 73-87 truck.. so 5 lug. The rear is a 6 lug off a '68 I think. (truck is a '68, but the rear axle isn't original, had 3.08s, he changed to 3.73s) First qustion. What is the length from flange to flange on the pre 71 rear, and what is the length on the 71 and 72s? I would like to measure to make sure I know what rear I have. Did 71s and 72s have 6 lug coil spring in the 3/4 tons? Second Question. Can I get the original axles redrilled for 5 lug? Or should I just spend the money on new axles.If so who has good prices? Money is kinda tight, and 70 rs/ss is going to send me some rallyes so he can get his tires and rims back that are on the truck now. They go to a couple of other projects he has, he just wanted to make sure that I had good tires for the drive home (what a guy!) I will get pics as soon as I can! I know y'all want to see. I can say that the 1400 mile trip went off without a hitch. And I got about 14 mpg going 75-85 the whole way. Damn 2 barrels are cool!! Thanks guys! Shawn __________________ 1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE

03-21-2007, 09:33 PM	#2
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Re: Question on rear axles... 71-72 were all 5 lug on 1/2 ton and 8 lug on 3/4 tons. If you have a 6 lug coil rear in it now, it's a 70 or earlier rear 1/2 ton. You can either get a 71-72 rear, order special conversion axles (ECE has em) or convert a 73-87 rear to work. I prefer the 73-87 rear myself. You have to weld new saddles on it and use a super track bar, but that's all easy. __________________ I'm on the Instagram- @Gearhead_Kevin

03-21-2007, 09:56 PM	#3
jorgensensc Registered User Join Date: Jul 2003 Location: Cypress, Tx Posts: 4,005	Re: Question on rear axles... THanks for the reply Kevin. So redrilling the originals is out of the question? __________________ 1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE

03-21-2007, 10:09 PM	#4
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,746	Re: Question on rear axles... Rear Axle Measurements MEASURED ACROSS WHEEL MOUNTING SURFACE 60-61" 64-69 1/2 ton 2wd Chevy/ Some GMC 6 lug rear end 12 bolt Coil spring set up 62" 70 2wd 6 lug rear end 12 bolt 71- Newer 2wd trucks use a 5 on 5 lug pattern You can have yours redrilled, IIRC you will have to have at least one hole welded to do this. __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI Last edited by neonlarry; 03-21-2007 at 10:10 PM.

03-21-2007, 10:11 PM	#5
Robznob11 Registered User Join Date: Feb 2004 Location: brownfield texas (west texas) Posts: 1,936	Re: Question on rear axles... got mine from moser for 280.00 shipped and they are non tapered 40% stronger than origanals, im not positive but i think that 70 1/2 trucks had 6 lugs but were the wider rear like in the 71-72 you might ask around... __________________ The Ghost 67 short wide full custom. 550 hp LSX, 4l80E, narrowed 9". Body dropped w/air ride! ........................ ___ .........________//__{\_____ ,,,,,,,/__(⊙)___//___/__(O)_/ @disciple2.rc 💪instagram💪 LED TAILS

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